imac keeps defaulting to "Automatically Log Out of a Mac After a Period of Inactivity"
2019 iMac, 16GB RAM.
Just got a new iMac from my employer. I am admin on this iMac, campus admin is also. I have all privileges - I can install and remove software, authorize non-apple developers etc.
In my profile, I change the setting "Automatically Log Out of a Mac After a Period of Inactivity" from 30 mins to none, turned off. (path: System preferences>Security & Privacy>General (unlock)>advanced) I use the proper method - authenticate lock to make changes, etc.
This defaults back to "Automatically Log Out of a Mac After a Period of Inactivity" (it auto sets the time as 30 mins) whenever it likes - but which I mean sometimes it doesn't do this. I have tried this by putting the machine to sleep manually, and found a hour or so later that it has logged me out despite the setting being turned off. It also reverts and logs me out if I do not put it to sleep.
This is very frustrating. The machine takes ages to restart and reopen apps, sometimes loses work and is running slower already because I need an external display (the problem has repeated without the display plugged in).
Anyone know how I can override this and make sure it doesn't keep defaulting? I have never had this problem occur after using Macs since 2000. Any help is very much appreciated.
iMac 21.5″, macOS 10.15