Re: Bugged every day outfits. Unable to fix.
In the video I had 4 outfits set up because I had been deleting and adding outfits testing stuff. I think at the time I first noticed the bug I only had a couple set up in the every day section. One of the sims in our household was brand new to the household too so she only had 1 or 2 set up as well. I'm fairly certain our other sims didn't have 5 set up when the bug happened but I'm not 100% sure about that. Not sure if we set up a club outfit. I don't remember doing that but she may have so I'll check in game.
I did try a few more things last night with the sims. I noticed when using some tray file utility that lets you track down cc used on your sim (we had none listed) that in the long list of items that I'm assuming were all outfits use by our sims the yfBottom_Nude thing was there even though none of our sims are actually set up in CAS to use it other than the bugged outfits. I didn't see other body parts listed as outfits in there but could have just missed them and this could mean nothing.
Another thing I noticed in testing last night is like what you suggested, making a twin. Several days ago when I imported a sim from the gallery someone had made I saw it wasn't affected, so it's specific to our current sims. Last night I separated an affected one one from the household, saved it to the gallery, then imported her back and the newly imported one while she lost all of her relationship status was not bugged. She did keep her skills and all of that though. I tried that with the entire household I had to delete nearly all of them first though since we had 6 so importing all 6 would be more than the 8 allowed. It did seem to work though! They lost all of their relationships though with all the other NPC sims and each other.
One question I have about doing that is are there any negative consequences other than losing the relationships that I can fix pretty easy? I saw their skills, fame, and traits and all of that were fine but we're pretty new to the sims 4 so I may be unaware of some other things that may need to be fixed. Before doing that and committing it to a save I want to make sure whatever I may need to adjust is something that can be adjusted.. If it's just a few minor things that I can fix in the cheat console or with MCCC then we'll definitely do that so we can get back to playing again.
