Test Configuration option in IWA realm is not showing any or all groups in which the test user is a part of. Sample screenshot below
ProxySG will only show a group entry if this group is mentioned in a policy. This is called Groups of Interest. Even if the user is part of a number of groups and none is referred in the policy, Test Configuration will always return results as in the above screenshot.
This is not a issue but an expected response. To find the groups in which a user is part of, use the command:
net user /domain user.name