you are right. I am facing the same issue on Galaxy A50 fingerprint scanner. what is the point of wasting screen glass. nothing is wrong with it. there are bugs in fingerprint scanner.
it's not a Software defect. There is few tricks to Set up Samsung phones these days. When you set up your new phone do uncheck all the options that shows optional and then click next. Factory Reset your phone and do the all the set up. See Geekyranji...