None of the Opportunities, Customers and Contacts would sync to NetSuite when triggered in Salesforce. The prompt says, "Sync Request Timed Out".
When this happens, it is mostlikely that the 'User to Send As' field has an 'Inactive' user configured.
To resolve, go to Salesforce and do the following:
1. Setup>Build>Create>Workflow & Approvals>Outbound Messages
2. Edit OpportunitySyncWithNS, set the 'User to Send as' field to your preferred user and make sure that it is 'Active'.
Please do the same with ContactSyncWithNS and CustomerSyncWithNS.