Map layer being randomly deleted

This is now the second time it's happened and I can't figure out why.  I've uploaded the maps from my computer into roll20, loaded them into the map layer and pain stakingly spent time lining the grids up. Only for them to be deleted out.  It doesn't seem to be on specific maps, it happens randomly. Last time it happened I logged back in every day to just check the maps, happy that they were fine I haven't logged in again since Friday. I have 5 maps currently loaded in for a campaign and on logging in this afternoon 2 of them have disappeared. Tokens and assets are still appearing but the map layer has just vanished.  Any ideas?

I should also add in that the GM Overlay items have been deleted out as well. 

Just checking the obvious - that no one else has GM access to your game? Are they disappearing from your assets as well, or just the graphic token disappearing from the canvas?

No I'm the only one with GM access. Looking in my asset library and the names are still appearing but the images aren't coming through and I can't re add them. Last time this happened I had to delete out the item and re-upload the items that had been deleted. 

I appear to have the same problem, especially with maps that either have been newly added or not used in a while. None of the maps from the dungeon masters guide work

This sounds weird, particularly the DMG maps. This sounds like something requiring Dev assistance. A  Help Center Request  will create a job ticket; devs are not as likely to see single threads, unless the problem starts blowing up.

Problem appears to be solved by it self. My guess is that it related to Network performance  (so anything from server-side, transfer over internet, ISP-problems, the local router or the receiving PC  :P  ) Might explain why recently used maps worked fine (because they are buffered). Fingers crossed for now, but with higher the usual pressure on everything online, I imagine we might see the problem in the future Suggested workaround is: Try to use the intended maps the day before the game, so that they buffer.