Has anyone else had trouble with supplier invoices not integrating across to Xero? How did you overcome this?
Has it been working and suddenly stopped, or are you using Xero and/or Neto Advanced Inventory for the first time?
Lots of things can go wrong with accounting integrations, they are pretty complicated. Check the logs under Xero > Logs and Reports to see if it's attempting to export purchase orders and if you're getting any errors. There's a list of errors and troubleshooting tips here:
https://galaxy.maropost.com/s/article/Xero-Common-Errors
Otherwise, you'll probably have to contact support. It's very hard to troubleshoot accounting integration issues without access to your account.