One chestnut from my history in lottery game development:
While our security staff was incredibly tight and did a generally good job, oftentimes levels of paranoia were off the charts.
Once they went around hot gluing shut all of the “unnecessary” USB ports in our PCs under the premise of mitigating data theft via thumb drive, while ignoring that we were all Internet-connected and VPNs are a thing, also that every machine had a RW optical drive.
During those 10 minutes of admin rights:
net user secretlocaladmin * /add net localgroup administrators secretlocaladmin /addThere’s likely a GPO cycling and removing all the admins.
This was my experience too. Shitty group policies messing with my local changes