Tee square

I love my 2012 Edge SEL with 128k miles, i call it my tank as it runs thru anything. However, 4 months ago my key fob stopped working for lock/unlocking the doors. I replaced the battery but still nothing. So I went to my spare and it worked fine until yesterday. Now it will lock the doors, but will NOT unlock them! Again i changed the battery and have the same result. Not sure how the sensor can read “lock” but not unlock and the other key, not at all! any suggestions?