users.settings.delegates List not showing delegates and Create not adding Groups

I've created a flow which creates a JWT token from a service account impersonating the mailbox account, it creates a Google Group based on some of the property names. Another JWT Token is created impersonating a bot account that has Group Admin role, this is to patch the group to hide from Address List (avoid people emailing it). The issues encountered are as following:

- When creating the Google Group, all is well, but when adding it as a delegate to the mailbox it keeps giving error saying "Invalid Delegate" however the delegate does exist in Google Admin and does work if manually done from the Mailboxes Account Settings.
- When trying to get details on extra parameters, I attempted a List delegate on the mailbox and keep getting a 204 response with the body being ""
Appreciate the help on this one 🙏