Ah, this is an absolute classic: openHAB has a bug, which it has had for a long time, where it doesn’t always properly load a Things file after it has been saved.
Restart your openHAB for a quick fix, or do this. To be honest, deliberately generating the error in the Things file is the fastest and easiest method as it forces openHAB to unload all the Things in that file. Repairing the Things file then forces openHAB to load all the Things back up.