marrok's tb omi is not working

it specifically says inquisitors are immune to percent based health damage.
Marrok was pretty much put into the game to make the reva mission easier (and baylon req)
today i watched as my entire team died from thermal detonators (a health percent based attack).

i've had marrok on the team for a few months and i've been able to get  reva shards consistently for my guild so... this isn't user error 

whats the point in getting characters that are supposed to help with missions if your game is just going to ignore their effects?