Bug: Curse on Hit from Creeping Frost/Greater Vortex Trap Expires Prematurely

I am using the Frost Ambusher Merc with a Curse on Hit item. The curse is correctly applied when Creeping Frost Trap or Greater Vortex Trap hits enemies. However, the curse expires after about 0.5 seconds.

This is inconsistent with how other Mercs interact with Curse on Hit. Please investigate.

Curses are removed when the applier (trap in this case) is dead/destroyed.