Unfortunately i had the same problem many times. Never found a solution. I can only guess some AI or algorythm is to blame for deleting stuff if it is deemed problematic in some way. For example i used red paint in splotches in one project and it got deleted every time. I can only assume that depictions of something like "Blood" are not allowed. After i changed it to green all was good. The simple solution would be to let us use our paintjobs without first uploading them but that is not possible it seems.