Unable to modify SSO with External Member account

Hi everyone,

Our client is using their Work force tenant accounts to manage the External ID tenant. The accounts are initially created as External Guests on the External tenant and then converted to External Members. However, they encounter the following error when attempting to modify SSO for some applications:

When we convert the admin account back to a guest account, it works. This issue doesn't occur with all applications, only some of them. Additionally, we have a test tenant where we cannot reproduce the issue.

Do you have any idea why this is happening? Also, is it possible to open support tickets for External ID? Under the "New support request" option, I can only see options for Billing and Subscription management.

Thanks a lot,

Dario