Not able to invite friend to and ultimate team game mode and only party

I have had an issue with the inviting , my friend who is on Xbox(I am on pc )  is able to invite me to party and game but then I am not able to invite my friend to my game but only party .Had this issue for a few days , gone to support but nothing has helped . Please sort this out as I want to play with my friend (we have everything enabled to let us play together ) .