Colored pictures not showing – Oil Painting Color by Numbers Review

I gave this app 5 stars because I really enjoy it and how the pictures look like photos. It is very entertaining and rewarding to finish a picture. But….. all of a sudden, my colored pictures are not displaying. Not fun to finish a picture and not be able to see it! Has this been reported before? Any suggestions?
Review by Kat's play on Oil Painting Color by Numbers.