If the direct integration between Dext - ApprovalMax - Xero is activated, Dext pulls data such as Tracking Categories, Account Codes, Suppliers, etc. from ApprovalMax every 24 hours.
When you create a new Tracking Category/Account/Supplier/Tax... in Xero, you should first sync this data to ApprovalMax.
To speed up the process of reflecting such data in Dext, manually reconnect ApprovalMax to Dext.