Oh wow, sure enough that did it. Maybe this is helpful: I was inspecting it with the firefox network inspector and with both English and Undetermined selected, clicking save doesn't send any network requests at all.

Something else weird, with only undetermined selected on the community, I was able to update the sidebar, but I was unable to reply to you (same infinitely spinning issue) until I reenabled both English and Undetermined on the community (I have both enabled in my user settings)