OK @soh I was futzing around more today and accidentally discovered a solution to my problem at least, see if it works for you.
1. Wake the device up using the power button. For me, the Hello camera won't activate. If I were to proceed from this point then neither the face recognition nor the...
Sounds like we're having a similar problem Soh. I've got a Surface Pro 7 with i7, and started on the insider builds as soon as they became available. After the 2nd or 3rd one I started having the problem where the touchscreen would stop working after the device resumed from sleep. Rebooting...