Data linked to the record being posted to BQE Core could not be found. Examples include linked projects, vendors, customers, accounts, and items.
This means you chose a name from the drop-down list for projects, vendors, accounts, or items, but that name has since been updated.
Solution: Now that you've recently run the sync, the drop-down list should be updated. Return to the bill and update the necessary data.
Detailed Example for this error: On Tuesday morning a bill is entered in BIll.com for a specific project named Project X. On Tuesday afternoon, the project name is updated to Project Z in BQE Core. Late Tuesday when you run the sync, the project name list gets updated in Bill.com to Project Z, but the vendor bill is not automatically updated. The bill cannot sync to Project X in BQE Core because it no longer exists in BQE Core. Solution: Navigate to bill in BILL.com, and choose the correct project name from the refreshed drop-down list and rerun sync.