It used to be owned by a player named sleukeleire and he had placed an extractor construction site on the H node.  It was not built, it was just a construction site.

I claimed the room and destroyed his extractor along with all the other buildings.

Then I unclaimed the room.

The player sleukeleire was able to RE-PLACE his extractor construction site on the mineral.

I am unable to place extractors anywhere unless I have claimed the room and have upgraded its controller.

It seems there is a bug that is allowing sleukeleire to continue to rebuild the extractor even though he no longer owns this room?

EDIT: I have since started reserving the room myself again, and his construction site remains.  There is no way for me to remove it without reclaiming it again which I cannot do until my GCL increases.