Insurgency(USMC, 1968)
tried to spawn in as a alpha Squadleader, then getting the mission finished sound. The scorescreen telling me "Mission Paused", klicking continue sends me back to the rolesheet and/or to the Mission vote screen. Here might be the connection to the missing mission module.

The missing mission module does not cause any error, but it just serves as a gentle reminder.

The getting kicked out issue is probably a result of Insurgency shutting itsself down and returning to the voting menu when no one is playing. This is to make it easier for players to switch missions, and to prevent the AI from going wild. When you switch roles it thinks no one is playing the mission, and will shut itsself down, which happens as you reconnect in (I think).