Ideas
Windows PC player, no CC
After the January update, my save data size was halved, and most of my photos became black.
Only those in my Sim's inventory were intact.
The only photos that remained intact on the wall were those that remained as copies in my Sim's inventory.
This led me to believe that photos that my Sim has copies of are safe to display in the world.
Also, since photos load normally only in the first lot loaded with untainted data,
I attempted to restore the blackened photos by uploading the photo room from a backup save to the Gallery.
(Open an untainted save → Load the house containing the photo I want to restore → Upload the photo room to the Gallery → Return to the main menu without saving ← Repeated this process more than ten times → Load the photo room from the Gallery into the most recent save → Hang the photo on the wall and make a copy, then add it to the Sim's inventory.)
This attempt successfully restored the photos from my camera and smartphone.
However, I was unable to restore my graduation photo and photo booth photos. They appeared to be saved in the Gallery, but I couldn't load them. (However, it seems that photo booth photos will not turn black when displayed if there is a copy in the Sim's inventory.)
I am very disappointed. I hope this is fixed as soon as possible.
(Translated from Japanese, sorry if the English is strange)