Time: Always been there as far as I can tell.
Frequency: Always.
World name: Brynhildr
Character name: Colette Pascal
Class/Level: Scholar/50
Party or solo: Both

If a party member (including the scholar) is between 25 and 30 yalms away from Eos and HP is below 80%, she will not cast Embrace automatically. Within 25 yalms, auto casting happens as intended.
Tested both Eos and Selene on Sic, Obey, Steady, and Guard.
Tested by placing faerie at max range (based on whether she has to move to cast), then changing equipment sets to lower current HP below 80%. The distance between her max of 30 and the point at which she started auto casting was approximately half the diameter of a shadow flare, which would be 5y.

I believe this is a bug because faeries are supposed to be fully capable on Sic mode, but this effectively cuts their range for Embrace down to 25y, which becomes very problematic if the scholar is healing from his or her max range.