Strongboxes don't open after all the enemies are dead.

This happened in a t17 ziggurat map with the following mods.

39 additional strongboxes
cursed by vulnerability
+1 maximum power charges
Area contains runes of searing exarch
40% increased magic pack size (via scarab)
Area's inhabitants are lying in ambush (from scarab)
Players which skills throw traps/mines throw 1 less
buffs on players expire 184% faster
Players are assaulted by bloodstained sawblades
Strongboxes have a 31% chance to be openable again (15% from scarab)
explocit modifiers on strongboxes have 75% increased effect (from scarab)


Not a single strong box would open after all the enemies from the strongbox died. It just comes up with the message "chest is locked"