Issue with Adding Users to Groups via Service Account – Inconsistent Behavior

Hi Community,

We're currently automating the process of adding users to groups in ServiceNow using a service account. The service account has been assigned the user_admin role.

When impersonating this service account, I’m able to add users to some groups successfully, but for certain other groups, the users are not being added, even though the system displays the message:

"Job has been queued to add users into group."

There are no visible errors, and the job appears to be triggered, but the users simply don’t get added to those specific groups.

Here’s what I’ve checked so far:

• The service account has the necessary roles (user_admin).
• The groups in question are active and not restricted by any custom logic (as far as I can tell).
• There are no obvious ACLs or business rules blocking the addition.

Has anyone encountered similar behavior?

Any insights or suggestions on how to debug or resolve this would be greatly appreciated!

Thanks in advance!