Just adding my experience here, it feels like the bug influences different saves with different severity.
For me when I first load into a household I haven't been in since the bug started (the September patch, everything was still fine during playing with fairies) the photos seem to be fine. However, if I don't do anything special, just hang out and play in that household for a while, save as/save (which is a routine for me, I still remember the very very early days of save not saving, and needing to hit save as instead, so I've always done both as a reflex for years) the next time I load in that household, the photos have turned black. Same happens with new photos taken, they appear fine at first, but at the next time I play they've turned black. Loading into the household after having been away from the game seems to be the point where the game checks sort of... 'were these photos saved or not?' status.
What is working for me personally at the moment (no guarantees for it working for others, nor that it stays this way) is that when I first load into a household that still has its photos, I do the whole song and dance of building an empty room, adding all the pictures there on the walls and saving that into my library as a precaution. So far getting pictures back like that has been working for me. Then I travel to another lot and back. Then I save-as/save and quit. Now the photos are still there when I load back in.
For any new photos I take I make a point to put them all on the walls and travel somewhere and back before quitting, and that seems to work so far.
However, the Moschino pack's digital frames that rotate photos in them don't understand this process and load only the top picture, the one visible when I load back in. The rest of the photo inventory has turned black. Even when I 'saved' those pictures earlier by placing them all on the walls and traveling elsewhere and returning. So for now I'm not using the photo rotating Moschino frames at all. (This makes me side-eye the soon-to-come event reward which is basically that frame for tables. If that's as broken as the wall ones, a whole lot of new people are going to find out about this bug really fast when that reward goes live.)
Paintings turn to white a lot in my save, too, but I've noticed a weird quirk. The paintings painted by the sim I had (auto) selected when I loaded in were fine. Paintings painted by people not in the household (gifted earlier in the save) turned white. Maybe just random, maybe something there.
TL;DR: what works in my save: (no guarantees for other saves, they all seem to break at different levels and ways)
- The first time loading into a household and seeing photos just fine: save them in a room to your Library. If you use Moschino's digital frames, take the photos out of them, every photo needs to be visible.
- Travel somewhere else and back.
- Save-as/save, then quit.
- Loading back into the household the pictures were fine.
- Any new photos taken need to be placed on the walls and you need to travel to somewhere else and back before save-as/saving and quitting.
- Stop using Moschino's digital frames until this is solved.
