Document header text not populated when posting MIRO invoice

Hi

When I post invoice in MIRO t-code, I'm populating the "document header text" field "Details" tab.

But, when I execute FBL1N report and apply layout - the document header text field shows no value (it is blank and is not showing the value I populated).

I looked at the table BKPF and the table entry for this field (BKPF - BKTXT) is blank.

Can someone please help me with this issue?

Thank you,