I made a post in !guitar@lemmy.studio from here on lemmy.ml, and then wanted to crosspost it to !guitars@lemmy.world (again, from here on lemmy.ml). When I clicked on the cross-post button in the original post, nothing I typed in the Community field seemed to pop up as a match for the desired federated community to cross-post to.
So I simply copied the URL, Title, and Body of the original post, but added [Crosspost] in the Title, and Crossposted from ... in the body with a lemmy.ml link to the original, and blockquoted the copied body text.
Original - https://lemmy.ml/post/1178638 Crossposted - https://lemmy.ml/post/1207214
If you look at them both, you will see these little tidbits
Original
Crosspost
So .. it did actually get recorded in the back-end as a cross-post, even though the front-end didn't look like it was possible. So is this a UI bug that you can't select a federated community as the destination of a crosspost? Was it the inclusion of Crossposted from <lemmy.ml link to original> that made it identify as a crosspost?