No, it is not a question of grip or angle, because it is not the sensor not recognizing the fingerprint but not working at all (being temporarily kind of blocked or sleeping and not reacting at all). I place my finger on the sensor, it does nothing, I keep the finger on it without slightest movement, and it suddenly wakes up after 5 or 10 seconds and recognizes the fingerprint.
I have a LED notification enabled in mce ( mcetool --enable-led-pattern=PatternFingerprintAcquired
) to indicate when the sensor is active, so I always know if it is a problem of fingerprint not being recognized (in such case the LED blinks but the screen doesn’t unlock) or the sensor not being active at all (no LED). And it’s almost exclusively the latter. Moreover, I can sometimes see that the LED lights up even when there is no finger on the sensor (e.g. when I place the phone close to some object) which then kind of blocks it for some time, like 10-20 seconds. So it looks that sometimes the sensor gets triggered by other objects than finger, which kind of temporarily disables it.
I have an identical (at least when it comes to size and location) sensor in Android phones (e.g. my mother’s Motorola G52) and they work for me in 100% of cases. My 10 III is the ONLY device that permanently gives me problems in this regard.
Lastly, I also identified the fingerprint daemon to be sometimes causing power consumption issues due to high CPU usage. This can be seen e.g. in Crest application - sometimes the /vendor/bin/hw/android.hardware.biometrics.fingerprint@2.1-service.sony
process starts utilizing a lot of CPU time - and this is most probably when it gets locked and doesn’t react to touches.