Baze Malbus has no ability granting him counter attack chance.
Chirrut's Indomitable Will text reads:
"Chirrut Îmwe gains +17% Counter Chance and Health Steal for each living enemy, doubled for Empire enemies. If Baze Malbus is present he also gains these bonuses"
If you kill Chirrut, then until Bazes takes a turn, he still counter attack you.
It seems that the effect of hitting Chirrut persists until Baze TM bar fills. I don't know if this is the intended behavior, because Baze is under the effect of that boost while Chirrut is no longer there.
I am assuming this is the case because I observed Baze countering and healing from his counter damage, (both signals that Chirrut unique was proccing), until he was defeated (and he never took a turn until then). However, it may not be aways the case if Chirrut is defeated right before Bazes turn.
Either this or the buff imunity is preventing only the display of the retribution buff, but not the retribution itself.
I have this small shot that shows Baze countering without Chirrut or Retribution present:
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