GOT IT WORKING
This resolved it for me on one of my Windows 11 machines.
the "old" Microsoft Store version of Enpass
Installed the 6.11.5.1823 version directly
Setup up enpass
When setting up OneDrive, there was zero issues
Working
The I got it also resolved on my iPhone, but had to uninstall Enpass from the iPhone first, then download the same version I had (since there was no update available before uninstalling) from App Store. And setup Enpass as new install just as I did on PC, and then sync worked fine.
So now onedrive sync works fine on one Windows 11 machine, and on my iPhone.
I will try on my next PC to re-install Enpass from the Microsoft Store, and see if it is just "re-install" that fixes it, or if I really need to download the 6.11.5.1823 from directly from Enpass. Will update with results later today.