Transaction MRBR is used to release blocked invoices and at times you might not find a particular invoice to release in MRBR. Many think that the all open items in FI that are blocked in status should exist in MRBR to release.
For example I had run an FBL1N report for open items with “R-Invoice verification” block indicator in the selection parameters. Usually all the line items shown in the report are expected to be available to release through MRBR. However in certain cases you might not find all them for release. Here are the possible reasons.
a. The invoice document is cancelled/reversed in the system and not cleared. Open item report does pull the invoice and its cancellation document and if there was an “R” block on the invoice it stays even after cancellation but this invoice doesn’t show up in MRBR and it is what usually anyone would expect to happen. After clearing in FI, this item disappear from open item.
b. If the block indicator was added manually to the invoice such as using FB02 etc. Invoice for which block indicator was added manually after posting doesn’t show up for release in MRBR. This is because MRBR uses a different structure RBKP_BLOCKED to track blocked invoices and it is not linked to the changes happening in FI. Maybe SAP thinks that invoice blocks initiated in FI area has to be released in or changed in FI only.
These two cases might help you to understand when you find an invoice missing in MRBR output.
FICO bites 