If you encounter an error (e.g. on trying to run an Enterprise overview report on your Netwrix Hyper-V VM) indicating that the SQL Server Reporting Services has issues with encrypted content, it's most probably due to the fact that the Reporting Services account has been changed.
Whatever the reason, the first logical step is to try to fix it by running SQL Server (2016, in this case) Reporting Services Configuration Manager and try to backup, restore, change the key - or (in the end) delete the encrypted content. However, you could run into a situation where only restore and delete content procedures are available - and the latter doesn't work.
In this case you're going to get a "Failed to delete the encrypted content in the report server database. Please execute the "DeleteEncryptedContent" stored procedure on the database manually." error.
The rest of this tip is therefore actually dealing with this, underlying SQL Server error.
- using your MS SQL Server Management Studio, connect to your Netwrix instance;
- expand the Databases on it;
- go to the respective database (by default it's named ReportServer$SQLEXPRESS);
- expand the Programmability options (as pictured below);
- locate dbo.DeleteEncryptedContent Stored Procedure;
- right click on it and select Execute Stored Procedure;
- when it's finished, disconnect from the instance and just try running Netwrix Report(s) again (eventually a service restart may be needed).