Just so you know, I was not in manual mode when I tried the upshift. It would eventually upshift if I did nothing, so maybe it was just coincidental that I pressed the butting and it shifted.
I have a 2025 powerboost and it has done the same thing when in tow mode. It seemed that if I pressed the upshift button on the shifter, it would then get unstuck. It has never done this in normal mode. Good luck getting a dealer to diagnose when it only happens on rare occasions.