That's... odd. I'll update the game and add an alternate keybind. Thanks for reporting.
You could also try uploading a Windows build. Sometimes special problems arise which are specific to the WebGL build.
There is a Windows build. In fact, it's the only one available.
Oops, sorry. I must have been thinking of something else when I replied. But I did try quitting and restarting a couple times and the issue was not resolved. Odd.
That's definitely quite curious. You're sure your Z key isn't broken either?
Nope... it works fine, like here: Z. I tried Moonbound again, no change. Kind of disappointing. Not sure if this will happen to anyone else.