File locked but only when run from Task Scheduler

[EMF]

I have a FFS_batch file that runs fine if you directly log in, run FFS as administrator, and click Synchronize. "Fail-safe" and "copy locked files" are both set in FFS. But the same exact batch file, when run through Task Scheduler, fails to copy in-use files:

[7:00:01 PM] Error: Cannot read file "C:\DB\2019.QBW".
The file is locked by another process:
QuickBooksDB24 [C:\PROGRA~2\Intuit\QUICKB~1.0\QBDBMgrN.exe]

I've confirmed (multiple times) that the scheduled task is set to run with highest privileges on a service account with admin privileges. It runs fine if I log into that service account or a separate admin account. But something's keeping it from working from the Task Scheduler.

Any ideas?