Cannot sync data with numerical values

I have 2 bases for 2 different parts to handle, I sync the invoice table to base constract and constract table to base invoice. When the base contract creates a new contract it will be synced through the base invoice. At the invoice table, the base invoice I link the record to constract no, and when I create an invoice that attaches the contract code, the contract information will be synced through the base contract, but one thing is the Invoice column no. it does not automatically show the corresponding invoice code.
This is picture illustration:
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I put the 2 base test link here:

  1. Invoice ( Sign up - Airtable )
    2.Constract ( Sign up - Airtable )