I have an issue where the usernames in my SSRS web portal do not match the usernames in the reportserver database. I am unable to add\delete users as we migrated the users from one domain to another. Now SSRS give me the below errors:
The user or group name 'US\DMTAdmin' is not recognized.

the above windows security group was changed from one domain to another. We are collapsing subdomains.
the interface is still showing the old AD name. The ssrs users table, however is showing the new domain
I have restarted ssrs services and restarted the ssrs report server. What can i do to ensure the webportal is seeing the actual user name? How can i correct the error as i cannot add\delete users from my report server now.