Yeah, the lady did it for like 5-10 minutes, then let it rest for another 5 minutes before repeating the process. The whole process took 20-30 minutes for mine as well. Seeing as to how these people working there have done this numerous time, it's unlikely that it was a problem with the application of the protector. If so, why would they put out a statement regarding the 30% faulty thing?
Also, to the person who mentioned the mate 20 pro, that one uses an optical scanner so it'll work with any screen protector.
Also, if the screen protector works as intended, after turning on the touch sensitivity setting, the effort required to unlock your phone is more or less the same as when you were using the plastic screen protector that was included. If you needed to press noticeably harder to get it to register, something isn't working properly. I've already registered and deleted my fingerprints like more than 10 times. Definitely not user error since it was working perfectly before, on the included plastic screen protector.
Also, for those whose protector is working like 70-80% of the time, you need to decide if it's something you can live with, cause for me, the fingerprint scanner worked like 99% of the time on the plastic screen protector. I'd rather just return it, and get the refund. What if a few weeks later then got problem? Might not be able to get refund then. That's my personal opinion, at least.
With regards to the plastic screen protector, Mobilestop has it at around $15, but I'm searching for anywhere that might be selling it cheaper, before I head over to get my Whitestone removed.