Records are not synced due to an Invalid Salesrep Reference
Sales Rep on the NetSuite side is set as an Employee without a Sales Role
Solution - Edit the Employee record and either check the Sales Rep field under Human Resource or specify a Role on the drop down (for those who are using Sales Team)
There are 2 or more Employee records in NetSuite that have the same email address.
Solution - As the lookup of Sales Reps are based on the email address, if there are 2 or more employees with the same email address, the connector is unable to determine which Employee to use as a Sales Rep. Make sure there is only 1 employee with the email address.