Xbox and pc crossplay

i bought ultimate game pass through microsoft and i keep trying to play with my console buddies and it tells them unable to join multiplayer session or session is full, what are we doing wrong? how can we fix it if so?

Devs response about it here; Xbox Game Pass PC - Failed to Connect to multiplayer or session if full - #6 by Avalanche_Pontus

The reasoning behind it; When did this get here? - #14 by Avalanche_Pontus