The problem of the unpainted surface.

This is related to a crash involving Ground.bin. A possible fix is to close the map after the first error of this type, open it with an archiver (WinRAR, 7-Zip), and also open the folder GameFolder/Editor/H5MMods/MapName/Maps/Multiplayer or SingleMissions/MapName/ and copy the Ground.bin and Underground.bin files (if they exist) from there into the map archive. After that, save the changes to the map archive, close it, and rename it. Make a copy (!) and check it in the editor. In most cases, this should solve the problem. P.S. I don't think this is a current issue, but just in case someone needs it.