Hmm.... thanks for confirming and oh, nice name if that is actually your name :foodndrink: .
When you merged your Thieves Den DLC, did you have two Unofficial patches? I had two for some strange reason one with an SSSB at the end. Maybe that is the problem since I merged two patches into the .esp?
I also didn't un-check 254 other .esp's (that's a lot of clicking lol.) I don't think you have to? At the end it gave me the option to save just the SM .esp .
The first part is my name, the ID is....well I started with that 25 years ago, you know, the ID.
As for the DLC merging:
Cleaned DLCs first with TES4edit
Merged the patches
The Thieves Den, yes, two UOPs.
First I merged the UOP (not the SSSB)
saved
Merged the seconf UOP (the one with SSSB)
saved
So that one I did twice.
As for deactivating all the mods, use OBMM, right click the list, deactibate all. Same for activating all. helps a bunch, just need to uncheck the merged esps.