administrator permissions on a SSAS database I had a third party company coming over and building ssas databases to produce reports.

They did, but now the DBA wants to have a look but I haven't got permissions, to even see those databases, as you can see on the picture below.

Can I grant myself administrator permissions?

I am system administrator. there is a AD group called SQLDBA and 



When right-cliking on the server-properties-security-Add-
then adding my AD group SQLDBA it says I don't have the permissions to alter the server object as you can see on the picture below.

I had previously added that sqldba AD group as an administrator to that box.



TITLE: Microsoft SQL Server Management Studio

Either the 'mycompany\MMiorelli' user does not have permission to alter the 'myserver\instance' object, or the object does not exist.
 (Microsoft.AnalysisServices.AppLocal.Core)



BUTTONS:

OK
The SSAS permissions are completely independent from SQL Server permissions.

If you don't have permissions, there is one hope:


  By default, members of the local Administrators group are also granted
  administrative rights in Analysis Server. Although the local group is
  not explicitly granted membership in the Analysis Services server
  administrator role, local administrators can create databases, add
  users and permissions, and perform any other task allowed to system
  administrators. The implicit granting of administrator permissions is
  configurable. It is determined by the BuiltinAdminsAreServerAdmins
  server property, which is set to true by default.


Source: https://docs.microsoft.com/en-us/sql/analysis-services/instances/grant-server-admin-rights-to-an-analysis-services-instance?view=sql-analysis-services-2017

I suggest you to read the link above and try to run your Management Studio using an account that is member of Local Administrators group of your SSAS Server