Here's the proof that it happened to me also. It happened only on the desktop/browser version, and it's due to messed up "Loading resources" when the game last updated:

When there's no moon-31045320_1584562838307967_8773806381074481152_n.jpg
When there's no moon-31052253_1584563011641283_7574897957254725632_n.jpg
When there's no moon-31100383_1584564238307827_1486224611887546368_n.jpg
When there's no moon-31073066_1584564431641141_5573374941698457600_n.jpg