About two weeks ago new xDAT updates started failing on all of my clients with VSE 8.8.  When I try to apply any new xdat file, I get a message saying "Error: unable to backup existing file.  Not enough rights: Line 12."  I also see events generated in the On-Access Protection logs saying that the attempt to write to the ..\MCAFEE\ENGINE\OLDDATS\ folder was blocked with the reason being "Prevent Modification of McAfee Scan Engine Files and settings by untrusted default processes."   I tried turning off the Block settings for all of the items in the Access Protection Common Standard Protection, but I still see the block.  I also saw the previous suggestions to update the root certs using the USERFirst_and_Verisign_and_Comodo_and_GlobalSign bat and registry files, which I've done.  After installing, I rebooted and verified that the certificates got added to my Third Party Trusted Root and Intermediate Root cert stores.  Problem still persists.

All of these systems are standalone.  I see it on both Windows 7 and Windows 10 clients.  All are currently at patch 11, as we don't have approval to go to patch 13 yet.