The NFC reader wasn't working at the East Stand entry point I used today for the Frankfurt game. I was directed to the box office by the assistant, but opted to mess about with the app for a few minutes to find the bar code and get in that way.
It was all a bit of a faff, and relied on a WiFi connection to use the app to get in. I just note from previous seasons the NFC connection never seemed to work at the East Stand gates (happy to be corrected here), and I always scanned the bar code which always worked.
So I'm slightly concerned that the Google Wallet version of the 26/27 season ticket is NFC only.