Map Did Not Spawn Rare Mobs, and Could Not Be Completed

Bug Report ID: #624545616

Bug Description: Zero rare mobs spawned on the map. Because of this, the map could not be finished for completion credit. Screenshots are attached that show that all mobs on map have been killed.

Repo Steps: N/A, appears be error with map generation.
Map Type: Oasis


Map with display open, showing zero mobs remaining


Endgame Map open, showing map currently being attempted


New map opened, showing that map shows as "attempted" despite it not be possible to complete.