Re: one of my sims is nude in load screen but clothed in game

@nelejake  Please try changing the outfit and using "save as" in a clean user data folder.  Move your entire Sims 4 folder out of Documents\Electronic Arts and onto your desktop, launch the game to create a new folder, and quit.  Then copy your save from the Sims 4 folder you moved to the new one.  (Saves are located inside the saves folder, unsurprisingly.)  Load the save, and reassign all of the affected sim's outfits.  Then "save as," quit, delete localthumbcache.package, reload, and see whether the problem is still there.  Your other sims will lose any cc they're wearing for the moment, but this is just a test on a spare copy of your save, so it doesn't matter.

If the sim still isn't wearing pants, try moving her into her own household, again just as a test, and again in the new Sims 4 folder.