I’ve read that it should be possible, but my experience seems to show that that is incorrect, that you need a login for every instance where you wish to make a post or comment. Could someone who knows clarify this?
If you need a login for every instance of Lemmy to participate in non-local communities, then that will, I think, be the #1 issue with Lemmy adoption, and the main reason folks bounce off.
I’ve been able to post on multiple communities in multiple instances with a single account in one instance. I wonder if you’re running into the issue where some major instances have defederated from each other. Which instances have you tried to post to from your lemmy.ml account?