Does the UA Mystic's "charming presence" ability let someone know after they've been charmed?

Question

In the mystic booklet for UA in 5e the description for charming presence is as follows:

Charming Presence (1–7 psi). As an action, you exert an aura of sympathetic power. Roll 2d8 per psi point spent on this ability; the total is how many hit points worth of creatures this option can affect. Creatures within 30 feet of you are affected in ascending order of their hit point maximums, ignoring incapacitated creatures, creatures immune to being charmed, and creatures engaged in combat.
Starting with the creature that has the lowest hit point maximum, each creature affected by this option is charmed by you for 10 minutes, regarding you as a friendly acquaintance. Subtract each creature’s hit point maximum from the total before moving on to the next creature. A creature’s hit point maximum must be equal to or less than the remaining total for that creature to be affected.

Let's compare that to the charm person spell, which explicitly states in its description:

When the spell ends, the creature knows it was Charmed by you.

Pair the comparison with the fact that there are no components to psionic casting (UA document page 9), and I don't see why someone would know they're being charmed.

Is there any reason that someone may know they were charmed on a successful save from the charming presence ability? Would the creature know it was charmed after the fact?

Answer 1

No, they will not automatically know they were charmed.

If it doesn't explicitly say, then going by the old mantra of "the rules do only what they say they do", then an affected creature may not necessarily know they were affected*

*Unearthed Arcana stuff is, of course, not quite RAW and is subject to change. A DM may decide to overrule this or decide that there is a chance (via a Wis save perhaps) that a creature realises that it acted out of character and that something may be up.