Actually I figured out that even after a full console reboot, I was being stuck back in a disbanded group and kept seeing "Visiting {Players} Base of Operatios" or similar. So seems the real bug is happening if you answer someone's call for help but it disbands before you've completely joined and doesn't give you any way to return to your own session. I had to answer someone else's call for help, join fully, then leave in order for my session to be my own again.