Ideas
I am playing the latest update, on windows 10. I play using the EA app, and have a few of the add-ons/packs. I do play with some mods and cc.
I have been having my one sim paint another by using the "paint from reference" option. The paintings turn out fine, I have them framed, and then I stick them on the wall. I normally just save by using the "save and exit" option. Logged back in the next day and the paintings were all blank/white. The first time this problem happened, I looked up the issue and found a post saying that it's a save issue with that option. The images don't save properly or something.
So the next day I had the sim repaint some images, and did the same. Except I did a "save as" save. Played a bit longer, did a "save as" save, and closed the game. Yesterday I loaded my save, blank paintings. I recovered a previous save. Blank paintings. A friend suggested I turn off my mods/cc. And I saw that suggested here before I wrote this.
So today I turned off my mods/cc and loaded a save. Blank paintings. I recovered a save, still blank. I loaded up a save, had my sim paint a new and framed it. Did a "save as" save and closed the game. Reloaded that save, and the painting was blank. So it's not my mods/cc as they were all off in the games settings.
The images that the game takes before the sim starts painting are being saved to my screenshot folder in the game's folder. Both the ones taken with my mods on and the one I took with my mods off. I saw some talk of similar issues, but it was mostly about custom photos going black.