Error when adding moderators to magazine 'this value should not be blank'

I'm trying to add a moderator to one of the magazines I created but I'm getting an error message 'this value should not be blank.' I can open an issue on codeberg about it, but I haven't found anyone else mentioning this issue and it seems like other people would have noticed by now if adding moderators is broken. So I'm posting this first to see if I'm missing something.

On magazine panel > moderators, there is only one field for username and I have tried filling it with @[email protected] and just @name and both of these give me the error message. I don't see anything required missing from any of the other panel tabs. I checked the dev tools and there is no hidden field apart from a token which looks ok to me.

I get the same error on mobile safari and desktop firefox.

If I'm missing something, please lmk.