bugged thermometer. remove it, and shift right click somewhere other then the reactor. Place it down somewhere. then pick it up, shift right click it on your reactor and place it where it should be on your reactor build. Hopefully should fix the issue it is having. They sometimes do that randomly... a slight bug in their new code. That was a fix I figured out mostly by accident when I discovered they can be linked remotely to a given location.
you might have to do this again later if it starts acting up again...
