Hello,
Thank you for posting here.
According to your description, we would like to know whether we could convert global group to domain local group. As Thameur mentioned, we could firstly convert global group to universal group, then convert to domain local group.
As you said, it works when we try to convert a global group to universal group before changing it to domain local group. We could discuss with your manager about the impact when we change the group scope. We hope that there is no problem with the scope of the group so that your application works properly.
For Global to universal, this conversion is allowed only if the group that you want to change is not a member of another global scope group (as long as it is not a member of any other global groups). For Universal to domain local, there are no restrictions for this operation.
If our AD environment is complex, and the nesting relationship of this group is also complex, and this group is used in many domains in the forest, we recommend that we check these first, and then see if we can change the scope of the group.
Here is a similar case, we can refer to it.
Convert domain global group to local.
https://social.technet.microsoft.com/Forums/windows/en-US/3cc3d71b-ca71-4d85-9a86-93579dae9fd4/convert-domain-global-group-to-local?forum=winserverDS
For more information about group scope and group type, we could refer to:
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2003/cc755692(v=ws.10)?redirectedfrom=MSDN
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-2000-server/bb727067(v=technet.10)?redirectedfrom=MSDN
Hope the information is helpful. If you still have problems, please contact with us.