Hi Julipower,
I have no idea as I’ve never bothered to lock my phones. I find it a waste of time when accessing them 
In all honesty, also, it’s my first custom ROM handset. Before, on google riddled phones one wouldn’t have known where my biometrics potentially ‘travelled’ to…
I’m sorry I can’t answer your question but I’m just not using that sensor. Old habits die hard and I don’t want to place my biometrics where they don’t necessarily need to be.
All the Best!
P.S. In this post @csi just said would get GS6 anytime now:
Maybe You could ask Him?