Your Integration Status shows the below error, and is preventing the publishing of documents to Xero.
Connection must be valid and open. and is preventing the publishing of documents to Xero.
Xero users publishing Purchase/Sales invoices.
To clear this error from the Integration Status, please do the following:
Go to the Integrate tab.
Click on the Re-Sync Xero Data button.
Republish the affected invoice(s).
Please allow a few minutes for the error to clear and the invoices to transfer over to Xero.