Sims randomly changing into different outfit without being prompted?

I have this strange little bug going on where sims will randomly change into a different outfit in the same outfit category as the outfit they had just been wearing (usually). Fx, my sim got married off their home lot in an outfit in their formal-wear category, and when I made them go back home, they were suddenly in a different outfit from their formal-wear set without being prompted to change. Another example, not quite the same sequence of events but same issue, they came home from work, went straight bed and changed from their work outfit to sleepwear, which then turned back into their work outfit immediately. For clarification, these are all outfits I have created - none of them are randomly generated, but my sims keep occasionally bugging over into another one of their outfits.

I haven't seen anyone else having this same issue so it's most probably a mod or cc-caused issue, but I just wanna know if anyone has any idea what could be responsible? I have WW and MCCC [both fully updated] which are the only mods I can think of that could impact outfits, but they don't seem to be causing the problem. Does anyone know what could be causing this to happen?

Edit: So far I've only properly seen it happen with one of my sims (its most likely happened with others and I haven't caught it) and the sim has no had a completely outfit randomly added to their closet? Please help :(