How to resolve Accounting Entries pending for closed period?

Accounting document type WE for MIGO is open in FBL3N for a purchase order. But accounting document RE for MIRO is closed for the same PO. Why is this difference happening?

When compared with ME23N for PO display, nothing seems out of place. I am unable to find the problem.

Please suggest solutions.

I have looked at GR/IR clearing posts but they're either unanswered or aren't relevant.