can some1 help me with a realms issue?

i play on xbox and my friend plays on pc, both of us are using java and they should be completely compatible but for some reason we aren't showing up on each others friend lists in minecraft and my gamertag doesnt show up when they search to try to invite me. we don’t think it’s a problem with the platforms. it’s most likely an issue with the friends list or something related. multiple people have joined the server before me so people ARE able to join. if all else fails i’m just going to try to download minecraft on pc and join from there.