Invoice line approval status is Inititated whereas at header level the invoice approval status is Ap

Hi All, I have situation were for one invoice the line level workflow approval status is Initiated but the workflow approval status at header level is 'Approved' because of this mis-match the invoice is not picking for payment.

The invoice has two line first line 1 PO matched and line 2 is manual invoice entry.

I would like to understand on what basis this type of scenario may happen to the invoice.

Thanks

Hari