I have not permission to edit my campaign

Your software
My Mautic version is: 3.2.1.
My PHP version is: 7.3
My Database type and version is: MySQL 8

Your problem
My problem is: I cannot edit campaigns

These errors are showing in the log: You don’t have access to the area requested

Steps I have tried to fix the problem:

I have been editing a campaign with no problems since I created. But now I cannot. Mautic tells me that I have no permission…

What can I do?

Can anyone help me with this? I don’t know how to solve it…

The issue seems to be very common, but I still cannot solve it. The exact message is:

You do not have access to the requested area/action