Hi there! I will take a look into this. For now, try changing the anchor value of the minimap marker on the plugin file, just as a trial and error problem:
By default is set to the same as the character sprites uses on the real map. So that is kinda strange that this is behaving like that... Maybe can be some problem on my end with calculations of the position of the minimap marker according to the size of the map and game window. I will have to investigate and let you know!