I'm currently working on an art gallery for my new hood. I've had my families paint the 'easle' paintings (Mona Lisa, Girl with Pearl, etc...) to get some genuine filling for my art gallery. This went well for quite a while, but at some point, the art work started to 'vanish' when I tried placing it in the art gallery. That is... according to the 'wall' it's still there: I can't place another piece on that part of the wall, and if I delete the wall, the art piece gets deleted along with it (and the simoleans it was worth are added to my sims money). So it's there... except that it's invisible. And every painting I add after that is invisible too.

Has anyone ever had this and does anyone know how to fix this? I'm really fed up with near-empty art galleries.