Im on PC. Xbox live friend shows as offline and cant join

purchased the game yesterday to play with my brother. I am on PC and he is on XBOX one. We appear to be offline to each other but we can send and receive invites to each other. When we try to join we get this error message.
Cross-platform play is not supported between your platform and that of the players game or group you are attempting to join.

error code C04T00R14X-01 506172740693

Other PC players have joined the match but for some reason i cant. I have the same version of the game. Same patch number.

I am having exactly the same problem and the same error, what can be done?