#No#

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can’t be targeted by any divination magic or perceived through magical scrying sensors.

True seeing

This spell gives the willing creature you touch the ability to see things as they actually are. For the duration, the creature has truesight, notices secret doors hidden by magic, and can see into the Ethereal Plane, all out to a range o f 120 feet.

RAW about targets

Targets A typical spell requires you to pick one or more targets to be affected by the spell’s magic. A spell's description tells you whether the spell targets creatures, objects, or a point o f origin for an area o f effect (described below). Unless a spell has a perceptible effect, a creature might not know it w as targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

The target of trueseeing is the one that receives it's power, so the first part of nondetection isn't working(can’t be targeted). True seeing is indeed a divination spell, but it grants truesight, that is not a magical scrying sensor. Thus the second part of nondetection doesn't work either.

Truesight

A creature with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form o f a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.

No

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can’t be targeted by any divination magic or perceived through magical scrying sensors.

True seeing

This spell gives the willing creature you touch the ability to see things as they actually are. For the duration, the creature has truesight, notices secret doors hidden by magic, and can see into the Ethereal Plane, all out to a range o f 120 feet.

RAW about targets

Targets A typical spell requires you to pick one or more targets to be affected by the spell’s magic. A spell's description tells you whether the spell targets creatures, objects, or a point o f origin for an area o f effect (described below). Unless a spell has a perceptible effect, a creature might not know it w as targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

The target of trueseeing is the one that receives it's power, so the first part of nondetection isn't working(can’t be targeted). True seeing is indeed a divination spell, but it grants truesight, that is not a magical scrying sensor. Thus the second part of nondetection doesn't work either.

Truesight

A creature with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form o f a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.

#No#

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can’t be targeted by any divination magic or perceived through magical scrying sensors.

True seeing

This spell gives the willing creature you touch the ability to see things as they actually are. For the duration, the creature has truesight, notices secret doors hidden by magic, and can see into the Ethereal Plane, all out to a range o f 120 feet.

The target of trueseeing is the one that receives it's power, so the first part of nondetection isn't working(can’t be targeted). True seeing is indeed a divination spell, but it grants truesight, that is not a magical scrying sensor. Thus the second part of nondetection doesn't work either.

Truesight

A creature with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form o f a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.

#No#

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can’t be targeted by any divination magic or perceived through magical scrying sensors.

True seeing

This spell gives the willing creature you touch the ability to see things as they actually are. For the duration, the creature has truesight, notices secret doors hidden by magic, and can see into the Ethereal Plane, all out to a range o f 120 feet.

RAW about targets

Targets A typical spell requires you to pick one or more targets to be affected by the spell’s magic. A spell's description tells you whether the spell targets creatures, objects, or a point o f origin for an area o f effect (described below). Unless a spell has a perceptible effect, a creature might not know it w as targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

The target of trueseeing is the one that receives it's power, so the first part of nondetection isn't working(can’t be targeted). True seeing is indeed a divination spell, but it grants truesight, that is not a magical scrying sensor. Thus the second part of nondetection doesn't work either.

Truesight

A creature with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form o f a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.

#No#

Nondetection doesn't hide you from divination spells, it simply makes it harder when somebody tries to detect you by a divination spell.

Nondetection

The warded creature or object becomes difficult to detect by divination spells such as clairaudience/clairvoyance, locate object, and detect spells. Nondetection also prevents location by such magic items as crystal balls. If a divination is attempted against the warded creature or item, the caster of the divination must succeed on a caster level check (1d20 + caster level) against a DC of 11 + the caster level of the spellcaster who cast nondetection. If you cast nondetection on yourself or on an item currently in your possession, the DC is 15 + your caster level.

As you can see there is nothing about countering True-seeing.

#No#

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can’t be targeted by any divination magic or perceived through magical scrying sensors.

True seeing

This spell gives the willing creature you touch the ability to see things as they actually are. For the duration, the creature has truesight, notices secret doors hidden by magic, and can see into the Ethereal Plane, all out to a range o f 120 feet.

The target of trueseeing is the one that receives it's power, so the first part of nondetection isn't working(can’t be targeted). True seeing is indeed a divination spell, but it grants truesight, that is not a magical scrying sensor. Thus the second part of nondetection doesn't work either.

Truesight

A creature with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form o f a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.