Boss Spawns...
By: Oshova
I have found out that there only really seems to be 1 active boss in a Cyrodiil dungeon at once. 2 if it has loads of bosses (5 or so). Also, they don't spawn on a rotation, it appears to be random which boss spawns next. This is mostly just a theory, but I am hoping to test it out at some point, with a person stood at each spawn point.
This was why we had trouble finding them in the dungeon.