Invoice with ID x and invoice number x not found in Teamleader.
Presumably the original invoice no longer exists in Teamleader. Perhaps it could be that you have created this invoice before, then deleted it and then created it again.
It is important to know that the synchronisation maintains a relationship table in an 'underwater' manner. This means that the invoice synchronized by the package is related to the entry in the accounting package. If the first invoice is deleted, this relationship is also broken and the link can no longer find the original invoice 'on the way back' and Teamleader gives the above error message.
When you delete original invoices, make sure to also remove the entry from the accounting package.
If you have more than 1 of these errors, it might be a solution to first remove the entries from the accounting package, have the package synchronize all invoices again with retroactive effect and then make the payments on the original invoice/entry.