Finder search parameters not working for certains variables in Financials REST API Call

Hello,
we are using REST APIs to integrate various applications with our Oracle Fusion Cloud (25C).
We are facing an issue with the filter finder when trying to filter all invoices for a specific BU or Legal Entity.

The following requests generate a “400 Bad Request”:

• fscmRestApi/resources/11.13.18.05/receivablesInvoices?finder=invoiceSearch;BusinessUnit=THE BU
• fscmRestApi/resources/11.13.18.05/receivablesInvoices?finder=invoiceSearch;LegalEntityIdentifier=FR123456

However, the following ones all work.

• fscmRestApi/resources/11.13.18.05/receivablesInvoices?finder=invoiceSearch;BillToCustomerNumber=123456
• fscmRestApi/resources/11.13.18.05/receivablesInvoices?finder=invoiceSearch;BillToCustomerName=CustomerName
  

We are unable to find the logic behind this inconsistency.

Thanks in advance for your help.
Cedrick