I have found that if you change the security settings for the screen timeout to "Instantly with the power key or when the screen times out" that the fingerprint scanner will work all the time. It seems that there may be a code issue when having screen timeout set to a different setting. It is defaulted at 30 seconds I believe.
To change the settings:
Lock Screen and Security
Secure lock settings
Secured lock time
Select instantly with the power key or when the screen times out
Since I have changed this setting, I have not seen any issues. (Day so far). I will report back if anything changes.
I've just had this issue. Mine is 3 months old. Today, when I woke up, I tried to unlock my phone with fingerprint and it didn't sense anything, like the sensor was dead.
I didn't want to reboot it or unlock with password, cause I was afraid it was a virus. A couple days ago, I clicked on a search result and, when I got into the website, the phone shaked and appeared one of those messages that you can't get rid if you don't press 'OK'...fortunately, I could close the page. A few minutes later, when I opened the internet browser again, there was a page with a porno video on the screen. I got really afraid that it had caught some virus and that it was forcing me to use my password to stole it.
But, I had no choice but to reboot the phone and insert my password. Then, it worked well again.
Happy other users had the same prob. So, maybe, I didn't caught any virus! And hope it doesn't happen again.
Same was happening to me, but i found that some apps are responsible for this. It has happened to me when i use mega downloader and recently with castle royale after the last update of the game. You guys should try to find which app starts the problem. I had to uninstall castle royale, i hope supercell or samsung fix this, i believe those are problems of compatibility.
When you open those apps the problem starts and even if you close the apps the problem persists until you reboot the phone. So you guys try to test your most common apps.
Same experience here. Has happened 3 times since I received the phone. Fortunately, iris scanning continues to work for unlocking the phone, but iris is not an option for most apps. So, just a tad annoying.