Consolidated companies & and & are different

What causes this issue?

The number of the affiliated company must be clear for the selected
document type for all line items. In this case at least two different
companies or a company in connection with a business partner who does
not belong to a company are stated.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

If you selected the correct accounts, you must enter the document with
a document type that allows cross-company posting. Otherwise, please
correct the entered account.

Error message extract from SAP system. Copyright SAP SE.