lenlec, my 2018 T6 was exactly the same. At first it was failing to unlock now and then, but got worse as time went on, and eventually would only open manually from inside. It appears that it is a common fault on the sliding doors. A friend of mine had the same problem with his T6. We both had them repaired under warranty at our local dealership at no cost to us. Ironically, when I took my van in to the dealership. their curtesy T6 bus (19 plate) also had the same problem! LOL. Must admit the VW warranty is very good, they have fixed faults a couple of times for me free of charge.