Hey @james10, thanks for writing in.
I just did a quick check and updated this setting to Trust Level 0 (virtually similar to “everyone”, though “everyone” includes anonymous users, which is technically not possible since users need to be logged in to use chat).
It should now work.
I believe the “everyone” group was causing problems because it’s not exactly a real group, and our plugin wasn’t doing a correct check here. I’ll update OP to indicate this gotcha as well.