Not sure the exact reason for this - have you looked at this article: How to Disable UAC Prompt for Specific Applications in Windows 10? | Windows OS Hub
Have you applied all the latest windows updates?
Try these steps
Shutdown all unessary services - AV etc
Empty your recyclebin
Run a freespace erase
Now try recovering the files, if a file is still recovered is it intact?
Do you have any third party data protection software running? shadow copies or RAID?
What happens if you erase a single file?
This is always caused by access to the disk being denied. Can you run a disk health check?
Also try shutting down as many services as possible before running the freespace erase.
Apart from AV software - databases like mysql can cause this issue