Hello. Two android Verizon customers (I'm on an S7, he is on a pixel 2) at my workplace noticed yesterday 12/20/19 that our phones reverted to being an hour behind but only while at work. I left work at 2:30pm on 12/20, my phone had reverted sometime after 2:15. I had it restart, it didn't fix itself. I double checked the network time settings and had it restart again while on my way home. It was fixed.
This morning on my way into work (5:45am) my 4:45 alarm went off just as I was getting off the highway. I checked and the phone had reverted again to being an hour behind just as I arrived back at work.
None of the iPhone Verizon customers at work reported the issue.
Not sure what's going on with it but since my smartwatch relies on my phone for the correct time, that's troublesome.