I had a situation a while ago where a device just would not work in a given room. I
posted about it here. I swapped out the device but the new one still had the same problem. What solved it was deleting the room entirely from the project and recreating it from scratch. Then manually doing a factory reset on the devices in the box and re-activating them.
It was the damnedest thing, but apparently there was 'something' about the way the project handled the room and the devices that just wouldn't work right.