its because in latest client, they remove most of the blank minimap and the client should read exceptionminimapnametable.txt (which have the list of all the exception map name), but it seems like the client isnt reading that.
If checking using hex editor, it have that txt content but still, I dont know why its not read by the client at all.
Let me know if you have some maps that are still have that issue, since I might missed any and I want to update that GRF too.