Many thanks for sharing this. I realised today that my mirrors weren't folding and looked on this forum to see if there was a solution. I have a 2015 Cupra and I used your tip but it didn't seem to work after several attempts. A few more searches and I managed to find this worked for me instead:
1. Take drivers window down slightly then back up to top immediately. When it reaches the top, hold for one second the release the switch and immediately pull switch to close again and hold for just one second.
2. Repeat to all windows
After I done this my mirrors folded perfectly.
Your tip helped me find the solution however so hopefully mine will
help others who may be struggling.