Riva Cloud or Riva On-Premise may fail to sync NetSuite users due to lack of permission to access deleted records.
Examination of the Riva logs would reveal an error similar to this sample:
[Opportunity] Poll Error - Insufficient permission, [Code=INSUFFICIENT_PERMISSION] Permission Violation: You need the 'Deleted Records' permission to access this page. Please contact your account administrator.
The NetSuite user configured in the Riva connection does not have the correct permissions set up in NetSuite.
User does not hold the necessary privileges to access deleted records
A similar error, Poll Error - [Code=USER_ERROR] You cannot perform this search, because you do not have permission to access employee data, can be fixed by following the same steps, except that at step 5, give full access to the Employee Record and Employees permissions.