Can't unlock System Preferences though i am administrator and know all passwords

I can't unlock the advanced system preferences. I click on the lock icon at the left bottom in Security & Privacy (I also tried in Users & Groups) and enter my password, i tried both the one for my mac and the one for my apple id but it just shakes and is not accepting anyone of them.

I have tried:

• Checking that i am an administrator. I am.
• Changing my apple id and mac passwords (3 times, both from the recovery mode, with the resetpassword command, in Users & Groups and on this website...)
• Deleting the system preferences caches in the Caches folder in Library.

This is not making any sense to me.

I have tried everything i have found when googling "Find my password to unlock System Preferences" and sentences like that.

Note: I have recently upgraded to IOS BigSur 11.1, and i have problems with running Virtualbox. I tried uninstall Virtualbox and install it again and needed to give permission to do that, and therefore ran into this problem.

Please help.