iPad Air 4th gen Touch ID stopped working

After a year or so of working fine, Touch ID is now completely non responsive. I have read the article, “If Touch ID isn’t working on your iPhone or iPad”, downloaded the latest software version as recommended, checked in settings, all on, fingers learned in….and it is none of the other possible causes listed in the article. To be clear, I open the iPad ( it is on a hard button keypad) it wakes up as usual, the prompt to open with Touch ID is right where it always is, I touch with either of the two fingers that usually work, and nothing happens. I can open with code.