I was unable to report this using F12 (received an upload error)
The mission objective in the UI say “Evacuate all Phoenix Point Operatives” or something to that effect.
We are there to rescue Ravi Chaudri.
I managed to evacuate Ravi Chaudri first and had the rest of the squad at the exit preparing to leave. The team was in overwatch.
During overwatch - the squad eliminated the final Synderion enemy. The mission ended.
The summary screen told me that I encountered overwhelming forces and was unable to complete the mission and that we needed to try again.
I have had this happen before. If you eliminate all of the enemy forces - the game should automatically credit you with being able to evacuate and completing the mission objective.