HTC 10 not always asking for pin on unlock

[V8Maverick]

My android is doing some kinda wierd unlocking things. I put the pin in on boot, that's what I wanted as it's encrypted, fingerprint scan all good, but the odd thing is that when fully booted it doesn't always challenge when unlocking. Press power button, swipe up, straight to home screen. Next time I try that I get enter pin or fingerprint. Seems to be entirely random as to whether it wants proof that I'm me or not.
HTC 10, Android 7, Encrypted

Oh, and the highly intrusive ads that take over the whole screen on here are bloody annoying. Just so you know androidcentral

 

[B. Diddy]

Moved from the Nougat forum to the HTC 10 forum.

Is Smart Lock turned on? What's your Automatically Lock interval set to (i.e., how much time the phone waits after the screen has gone to sleep before it requires your PIN again)?