The item enchantments reliable, predatory, deceptive and probably also the others from the attack resolution group are not triggering (extensively tested with multiple items). Spell with the same effects like displaced image and merciless gaze do work.

 

I haven't found anything online. If this is known, can somebody tell me how to resolve this?

I have run further test and they do trigger but not at 10% or 20% rate. Its rather around 1% to 2%. From 115 hits only 2 were converted with predator and from 41 grazes only 1 was converted with reliable.