Does the fact Spirit Guardians has range self, affect whether the area of effect goes around corners?

Question

Spirit Guardians has a Range of Self (15-foot radius) (and adds in the description that the Spirits "flit around you to a distance of 15 feet for the duration")

Given this situation:

The cleric (in yellow) casts the spell. The door to the room below is open but the cleric does not have line of sight. Does the foe in that room take damage at the start of their turn?

(Note that the topology here makes moot other questions addressed on this stack as to whether the spell is centered on an adjoining intersection or on the caster, or what the shape of the radius is.)

There is no line of sight between the cleric and the foe. If it were a Fireball she were throwing at her feet, the foe would be affected, because the description of Fireball makes mention of going around corners. The language of Spirit Guardians is not nearly so clear. The discussion about Spike Growth here (i.e. "you cannot target a point that is blocked by total cover.") doesn't seem to apply, because Spike Growth is targeted, but the Spirit Guardians are not.

I see three answers:

1. Yes, because the Spirits flit within the given radius and, like a Fireball, as long as nothing is totally blocking them, they fill the area.
2. Yes, because the foe is within 15 feet moving distance from the cleric, which is how far away the Spirits can go. In this case, the actual area of the spell would not actually being a circle is affected by travel distance from the cleric; the table at the bottom of the image would actually be out of range because of having to go around the corner into the room.
3. No, because there's no Line of Sight between the cleric and the foe, and the Spirits don't go around a corner. If she moved left a square of two, she, and the Spirits, would be able to target the foe.

Answer 1

Areas of effect only go around corners if the description says so.

For example, take fireball. The area of effect of fireball spreads around corners because the spell description of fireball says:

The fire spreads around corners.

The reason this needs to be said is that the rules for areas of effect state:

A spell's effect expands in straight lines from the point of origin. If no unblocked straight line extends from the point of origin to a location within the area of effect, that location isn't included in the spell's area. To block one of these imaginary lines, an obstruction must provide total cover, as explained in chapter 9.

Since spirit guardians contains no statement that it spreads around corners, it does not spread around corners.

Answer 2

The spell says, as you quote, the spirits:

flit around you to a distance of 15 feet for the duration

Based on the image provided, and that the foe is no more than 15ft away, it seems as though the spirits could 'flit' into that square.

Given the definition of 'flit':

3. to move in an erratic fluttering manner

Implies they can 'move' to all squares 'around you' so long as they stay within 15 feet. Nothing in the spell text says about them being incorporeal, so as you surmise, they cannot pass through walls, but perhaps a kindly DM would allow them to move more than 15 so long as they stay in range.

I'd be inclined to allow this as nothing limits/specifies the amount movement they have only their range.

The difference with 'spike growth' is that it states the affect area:

sprouts hard spikes and thorns

Implying that once sprouted, the growth takes no further movement.