Hi there,
This issue occurs if the group has a member from another forest whose account has been removed from the account forest. The member is represented in the local domain by a Foreign Security Principal (FSP).
To resolve this issue, enable logging for the resolution requests that concern these SIDs and that are performed by the Active Directory Webservice.
Here is a link for a detailed description of the process that you must follow.
https:// learn.microsoft.com/en-us/troubleshoot/windows-server/identity/get-adgroupmember-error-remote-forest-members
"Unable to process the request due to an internal error" After AD Upgrade
-------------------------------------------------------------------------------------------------------------------------------------
--If the reply is helpful, please Upvote and Accept it as an answer–