This exact issue is happening in now my second save. Interestingly, I found a strange workaround to making them change to your edited state! It might be just a fluke, but I realized it had been doing it every time, so I kept testing it, and sure enough... after loading into the save and finding the Gallery sim in their original form, I click on the shower and they revert to the edited version I created! (The game needs to be unpaused to take effect.) You don't even have to select an option from the shower, just click on it. Worth a shot to try in your game? I originally had the Internal Wall Shower Head (Lovestruck), but also tested it with a few other showers and they all seem to do the trick.
This seems to be working for me for now, thanks for the tip! I still hope EA fixes this still
