I have experienced this issue twice before; it seems to happen on occasion when I revive a dweller that has died previously. This most recent incident occurred in my greenhouse (2nd level garden). I have attempted relaunching the app, but to no avail. I have not attempted reinstalling it, as from what I can infer, that would most likely delete my save file. A temporary workaround I've seen is to delete the room and rebuild it, but I can't exactly afford to do that given the cost the build and upgrade it. Nor do I want to resort to that if this invisible corpse bug will be as common as it has shown itself to be to me.
Hello!
I have the same problem, but I can not delete the room, because this is the biggest barrack on the first floor and my shelter is full of dwellers, so its not possible to delete the room ("Cannot destroy this room since your Vault would be overpopulated."), for that I need to kick out a lot of dwellers from the shelter to create enough living space, and I do not want to do that... Also, I think, that is not a good method over and over again in the future....
(sorry for my poor english, hope understand it)