After Testing multiple times with my modules.... Dungeons made in Dungeon Maker.
Sometimes characters will NOT gain exp while going through them. Or they will not gain EXP for the first part of the module, but then suddenly start gaining EXP about half way through the module. This appears to be on and off.
The most recent I've been able to track was in Ruined Keep of Agramar where the characters will only start to gain EXP after the Second Large Orc attack area in the middle hold.
I can recall Hidden Shrine of Dramacht actually giving EXP... but Also remember Crypt of the Wight King also had on and off EXP gain.
Obviously the files are up on Nexus if you want to take a look through them for corruption.
I have not been able to pin this down at all, they just won't gain EXP until a little ways into the Dungeon no matter what they kill.