OneDrive Personal Vault Failure

[BERact]

I opened FreeFileSync and it installed the latest program version. When I went to run the backup of my OneDrive Personal Vault, I got the following error.
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Cannot set directory locks for the following folders:

Cannot write file "C:\Users\exact\OneDrive\Personal Vault\sync.ffs_lock".
Error code 0x1c0: The path cannot be traversed because it contains an untrusted mount point. [CreateFile]
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Ignoring the error also failed. Please help.

Onedrive folders outside my Personal Vault run just fine. My Personal Vault was unlocked when the backup was attempted.