Each user can only change a community tag once, and a community tag can only be changed so many times before it becomes locked. Edit: I can change it, so I assume you tagged it once already?
I tried to change it and got an error and now I can't change it
I know how community tags work - which is why it confused me that (1) it didn't change after I tried to make it, (2) it refused to allow me to actually change it afterwards.
Sorry, it's broken for me too.