Mephisto Aura not triggering vs Boss on uncollected event 2.2

Grimm

I fought the tech sentinel as a boss for the uncollected event quest chp2.2 - Invasion

I used Mephistos L3 when boss reached full 3 bars.

His permanent aura was not triggered.

I read the sentinels description and all the buffs on that node. There is nothing that indicates that this is an expected behavior.

I therefore believe it to be a bug.

can you please confirm that you will look into this?

Thanks

Grimm

Did anyone try this? Or had this issue?