[bbsc]

sounds like one or the other is setting the hardware clock with the local time zone

No, both are correct. I suspect that Linux synchronizes RTC to UTC and M$ - to the local time.
Ok, I'll try to use a scheduler task for ntp query under Windows, this may help.

the TPM chip isn't usable by any OS other than ChromeOS, and it's not needed for Bitlocker

Sad to learn.
It's really needed for Bitlocker if you only don't like to enter PIN during boot process or use a USB stick for key storage.