Strongboxes do not drop loot and say "This chest is locked" (in a Citadel map)

This is happening in a Citadel t17 map with the following scarabs:
Ambush of Hidden compartments
Ambush of Potency
Ambush of Containment
Ambush of Discernment
And Ambush on the map device

The strongboxes can be clicked to make the enemies spawn however they don't open and drop loot after killing all enemies. Happening to multiple (possibly all) strongboxes in the map.

Clicking them again triggers "This chest is locked" message in chat.

I searched and cleared the whole map except for the boss to ensure mobs were killed. It says "1 monster remains".

In game bug report reference is 3,776,399,265

i had the same twice now ... i know its because of the Mod "Searing exarch Runes"

Ah, yes I think I had searing exarch runes too