Code for lock screen doesn't work

Hi everyone,
I’ve updated my m2 note to 5.1.6.0. since then, my code to unlock my cellphone anytime the screens turns off isn’t displayed. I unactivated the code, set it back, but still, it doesn’t work though on 4.5 version I had no problem.
Does it happen to anyone ?

Ok. I deactivated networks and localization.
It seems smart unlock is working now. I activated it on a previous cellphone (Asus Zenfone 2) for localization AND detecting my smart bracelet Mi Band Pulse.
The problem is that I have no idea how to access the Smart Unlock function on Flyme OS 5.1 as on regular Android…
Has someone got any clue ?

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