Unfortunately all I can do is commiserate with you. My niece dropped her 6 Pro and cracked the screen so I ordered a replacement and installed it. After three hours of messing with the fingerprint sensor, I was in the same position as you; it's like it's not even there. No error message, calibration goes fine, but it just doesn't do anything.
I ordered a replacement sensor and have it sitting in my parts drawer waiting for an opportunity to swap out the original for the replacement and see if that does anything, but my niece isn't in any hurry so I don't know when that replacement will happen.
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=== Update (11/07/23) ===
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There is one big difference though; she doesn't have any issues with overheating or battery life or anything like that.
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Also, note that the screen I installed was an aftermarket screen, not a genuine Google part. In the time I've been hanging around on iFixit, I've observed that the genuine Google replacement screens seem to have a higher than normal incidence of problems. I am kind of chalking it up to quality control issues with Google's replacement parts department, so I have to wonder if it might be worthwhile to see if the repair shop will swap the screen out again to see if it will resolve some or all of the incidental issues you're seeing.
Unfortunately all I can do is commiserate with you. My niece dropped her 6 Pro and cracked the screen so I ordered a replacement and installed it. After three hours of messing with the fingerprint sensor, I was in the same position as you; it's like it's not even there. No error message, calibration goes fine, but it just doesn't do anything.
I ordered a replacement sensor and have it sitting in my parts drawer waiting for an opportunity to swap out the original for the replacement and see if that does anything, but my niece isn't in any hurry so I don't know when that replacement will happen.