On the Leon Mk 3 and Mk 3.5 (not sure about Atecas sorry) its only the front doors.
IF one was not working, it would be easy to say its simply a faulty unit, but with neither working it could be a number of things.
Is there anything not working, like foot well lights etc. That could suggest a fuse.
Have any
OBD style modifications been carried out? If so that suggests someone could messed up the software behind the scenes with Carista or OB11. In that case you're likely going to need to do some troubleshooting, or pay up an expert to diagnose and fix like
@East Yorkshire Retrofits.