Thank you, the lack of an @ symbol was the problem! I'd tried it without the exclamation point but hadn't tried substituting an @ symbol. And it seems like the link to it from my reddit instance didn't actually exist until I managed to get to it form the search bar.
I can't see any posts in the community from kbin for some reason, though -- do communities federate separately from instances as a whole?
...You can crouch dash?