Hey
@meltingspace,
Unfortunately, Mobile Terraria's minimap files are currently not compatible with PC Terraria. We're looking into the possibility of supporting this in the future, but as of this moment I can not make any promises. I
can however manually convert your minimap to a PC compatible version. If you are comfortable sharing it with me, I'll get right to it.
For the time being, you should remove the minimap file from your character folder: because the game can not overwrite it, it will discard all your new map data every time you exit your world.