User addedto the AD groups were unable to log into Spectrum. The user account was verified to be added by Spectrum, but not to the correct groups. Instead, Spectrum put the accounts at the root of the access tree, but without any privileges.
All supported version of Spectrum
The user account was created under the appropriate group in Spectrum. However the user record was incomplete.
Because the record created was incomplete, the record need to be removed first. There after, the user can attempt to login again. This will recreat the user record and the account is populated with the correct/complete.