Face ID Not Working [Fixed. Please see the approved answer for details.]

To those posting that installing version 7 fixes the problem - it doesn't. I'm still on version 7 and have been having this problem (and I'm having it right now) since I got an iPhone in July. Un/reinstalling version 7 does temporarily fix the problem but it always comes back sooner or later. For me, at least, this is not a version 7 vs. version 8 issue since I've never used version 8.

This is a massive and recurring headache for me since I use a strong master password and don't know it and don't carry it with me. I rely on Face ID on iOS to access my passwords (I used the fingerprint reader on Android which always worked fine). So if I'm away from home and need to get a password (like last week when I was traveling), I'm just screwed (like last week when I was traveling). This really, really, really needs to get fixed sooner rather than later. If it doesn't get fixed soon I can't I can't keep using 1Password and have, for now, stopped recommending it to others.