If the phone idle for a little while it won't event engage face unlock (not 4 hours idle security measure) You need to use a fingerprint to unlock first then it starts working again. It's intermittent.
1.Is this issue still reoccurring on latest firmware update .92?
2.Have you tried removing current face data and then adding it again?
I was trying to find 92 update but don't find it
On .92 update and re-added face data but the issue persist.