Yeah, it seems like the visualization of the available door positions does not work properly after a level is generated. The visualization uses Grid components in individual rooms so it's possible that there must be some offset added to their positions when not in the prefab mode. However, this should not have any effect on generated levels - it's just a visualization used when creating room templates in the Editor.
I created an issue on Github to check this later.
Also, the Isometric example is far less popular than the classic 2D ones so it's possible that there are still some problems that were not yet found. Please let me know if you find any and I'll try to fix them.

