Oracle is not identifying Receipt Customer based on Invoice if MICR is present in the Lockbox file

Summary:

Why is Oracle not identifying the customer details on Receipts based on Invoice number given in the Lockbox file if MICR is present as well in the same file?

Content (required):

We are trying to load the receipts (format- Extended BAI2) file from third party source system. However, we are not storing customer MICR information in Oracle fusion.

If we provide MICR information and correct Oracle invoice# in BAI2 file then Oracle is looking for the customer based on MICR information only. It is not considering the invoice# in that case to find the customer. Now, as no MICR info is available in Oracle the receipts are getting created as unidentified.