I had exactly this problem. My account was logging automatically when I opened sketch-up from my favourites bar. Then one day I was prompted to log in which I did but, from memory, I had to use a trimble login not my google account and suddenly I had no files . . and sketchup auto-logged in to that every time I launched it from then on showing me no files . . I just manually logged out and logged in using Google credentials and all my files are back . . It would be nice if both log-ins pointed to the same account . .keep well everybody