The integration between Xero and Workbench does an hourly sync automatically, if you have just added the Contacts please check again in one hour.
The contacts will also need to be added to the Workbench AP / Workbench AR group in Xero and have a unique Account Number in Xero.
Alternatively to manually trigger a synchronization between Xero and Workbench, please go into the Xero Integration screen and perform the following steps:
1. Ensure "Company" checkbox is ticked.
2. Back-date the "Last Update" field to an earlier date.
3. Click "Save" to save the date.
4. Click "Import" to start the sync.
5. Wait for a minute, then click on the "Test" button.
6. A table will appear below to show what has been added or updated in Workbench.