User is trying to get payments from Xero into CORE, but they are not transferring even though the sync settings are correct. User also wants to send invoices as PDFs from CORE to Xero.
Before you get payments from Xero, make sure the related invoices are available in CORE and are mapped to Xero. After that, go to Sync Settings > Get > Payment settings to check if there is any date range or filter selected. If so, make sure your payments are within the date range, otherwise Xero doesn't send the data to CORE.
Currently, you can't sync invoices as PDFs to Xero. CORE only sends the invoice data, which is handled by Xero in its own format.