I just want to report this bug about not being able to extract after completing the kullervo mission then leaving squad to farm for resources on solo. If you're not the host when leaving the squad you'll get stucked and the exit portal shows waiting for others to extract even tho you already left the squad. It's just too much hassle and that the resources and mission rewards you got won't be saved if you try to leave mission.
Just encountered what sounds like the same bug? Whoever the host was left after killing the orowyrm in a Kullervo mission. The other three of us reloaded into the courtyard that you exit from, but none of us were able to actually exit the mission. Forced to DC in order to leave, which also lost me all of my mission rewards (including the last bane I needed) even though it said I should keep all rewards up to my last decree being earned....