Primary group membership is neither reflected in the Member Of (in the member properties) nor in the Member (in group properties) attributes. Instead, members get the Primary Group ID property populated with the group identifier that is stored in the Primary Group Token attribute of the group. This behavior is by design in Active Directory and is not related to Adaxes.
According to your screenshots, there is only one member of the Domain Contractors group for which the group is not set as primary. For the rest 441 accounts the group is set as primary and thus they are not present in the Member property, but are displayed on the Members tab as they are members of the group according to the Primary Group ID value in their accounts.
For an example on how to get the Primary Group ID of an account and then use it, have a look at the following script from our repository: https://www.adaxes.com/script-repository/remove-all-group-memberships-for-a-user-account-s33.htm. Should you still have issues updating your script to work as desired, please, provide us with all the possible details on the required script and we will help you.