Hi 
Tom ,
UPDATE: it was server I presume, picture updated by itself.
Sorry to bring up the old thread (could not find other ones) but the problem is still here.
The problem: tried changing the picture of a game on Scirra Arcade, does not get updated. Already tried following:
1. Changing the picture (I thought problem was in the picture, so i changed it)
2. Both .jpg and .png formats
3. Cleaning the cache of the browser + hard refresh (Firefox 45.0.1)
4. Other browsers and other computers (Mac and Win 10) - Safari and Edge
5. Wait for server cache - at least 12 hours passed since the attempt.
Could you please suggest something? I ran out of solutions