Cannot Publish a Pbix file

Are you running basic, custom auth or windows authentication on the report server?

https://docs.microsoft.com/en-us/sql/reporting-services/security/configure-basic-authentication-on-the-report-server?view=sql-server-ver15

I'm guessing since you mentioned AD the answer is windows, and you're hitting an issue with your windows username not being listed explicitly in the security settings of your Report Server, but the user is an admin on the machine (and thus part of the builtin\admins group which is listed). The solution could be to explicitly list your username in a folder (or root) security tab of the report server.

To do this you can run chrome, edge, or IE as administrator (right click on short cut-> run as administrator) then click the "manage"  button on a folder of your Report Server, then click security and add "{Domain}\{Username}" to the list with all roles.