Mirror of Delirium Not Triggering

Walked through a mirror but delirium fog did not trigger correctly.

Event counter and stop button appear but the fog did not progress from orginal mirror spot, laeving small fogged area did not trigger timer and no mobs spawned.

Map type Fortress

map mods
increased magic monster
increased rare monster
+1 level of monsters
monsters have posion chance
mirror of delirium
increaded quantity of items
increased rarity of items
increased waystones

same thing happened to me on this map