This was a hard one to Google. Turns out, upgrading in-place from Windows 8.1 to Windows 10 resets NTP settings to defaults per Microsoft. Solution is to either unregister and re-register w32tm or create a GPO for NTP settings.
w32tm /config /manualpeerlist:pool.ntp.org /syncfromflags:MANUAL Stop-Service w32time ; Start-Service w32time
This sets the manual (as opposed to domain) NTP peer list to that on pool.ntp.org, specifies that the sync should be from the manual peer list, and restarts the w32time service. You should immediately notice the system clock being accurate. You can troubleshoot NTP by running:
w32tm /query /status w32tm /query /peers w32tm /query /configuration
You can force a resync by:
And per Microsoft, you can set w32tm to its default configuration by:
net stop w32time w32tm /unregister w32tm /register net start w32time