The ApprovalMax for Xero-Dext integration supports only Expenses to be pushed from Dext to ApprovalMax.
If you also need to push your Credit Notes from Dext to Xero, you can set the Dext-Xero connection as the primary one and the Dext-ApprovalMax for Xero as an additional connection.
This is how you set up ApprovalMax for Xero as an additional integration in Dext:
In Dext, go to Connections > Integrations
On the Xero Settings tab, click on Set Additional Integration:
Select "ApprovalMax for Xero" and click on Connect:
On the next screen, click on Connect Software:
Select "ApprovalMax Organisation connected to Xero" and click on ALLOW ACCESS: