You have been disconnected
AFTER completing a mission and going through the rewards / xp / recognition screens, the game boots me to the home screen VERY often instead of going back to Kelvin's Cairn, with "YOU HAVE BEEN DISCONNECTED." It's nice that you can complete the mission, but it is quite a hassle that it disconnects you so often after a mission...Come on please...
I encountered this issue on PC, using XBOX Game Pass. I also play on XBOX Series X.
I was playing online CO-OP
I was playing as multiple Heroes.