I got this combat round:
You pray for protection.
The eye focuses its gaze on you. You feel a strange tingling, then start bleeding as a hole is bored into your flesh, dealing 4 etheric damage, but it seems your prayers are answered to block all of the damage.
which normally would give Entrapping Gaze, except I didn't get any. So I think if you block all damage, you don't get the effect. That's not unprecedented.
However, the oddity is that the Bore Hole in Flesh page says "Gives 1 turn of Entrapping Gaze (applied before damage)". But if the effect is applied before damage calculation, it wouldn't know if all damage was blocked and could potentially result in an infinite loop of recalculating damage? So something not correctly documented there I suspect.
EDIT:
At 6 ED:
Entrapping gaze did 2-4 damage when all damage was blocked (gained no Entrapping Gaze).
Entrapping gaze did 2-4 damage when all damage was not blocked (gained Entrapping Gaze).
8 base damage seems correct, but the effect does seem to be applied after the pass/round. Not sure how that interacts in multi-opponent fights.