Known issue. Less of a bug than more of the consequence for escaping the trap via recall or teleport. The dungeon should reset after staying at an inn or if enough in-game time passes for the dungeon to reset. Typically shouldn't take too much in-game time to pass.
Once the trap is sprung, the gate is only lifted when all the enemies are killed or the lever is flipped. Neither is possible if you magically flee the crypt.