Alchemist's mark proc

Can someone explain me why alchemist's mark isn't working every hit on different mobs? I'm playing Mamba strike and using combo with AM with Battlemage's cry. Sometimes it procs with first hit, then 3 hits without it, then mark procs again. Sometimes it's two-three times in a row. Does it have hidden proc chance or what? I've tried with mark on hit sup - everything same.

I have 105% poison chance, and 99% chance to hit.

I'm finding the same thing. I'm not really sure what else to try though.

The suggestions I've seen so far are make sure you have enough mana, make sure the attack isn't missing.

Did you find a solution to the issue?