flex 2013 back left door is closed, but the dashboard sais it s not

Spray 'bunches' of WD-40 into the door *latch* - close / open door several times - you're trying to free up the sticking door ajar switch which is located 'inside' the door latch assembly. This works MOST of the time. I'd go ahead and do ALL doors same way while at it. Good luck!