Credits are not getting applied to the invoice while processing payments

Summary

Credits are not getting applied to the invoice while processing payments

Content

Hello Friends,

I am trying to process payments for 4 invoices. One is $300 and other three are credit $-50 each for a vendor. The vendor has other payments too. But what I do is I dont select "Apply Credit up to zero" but instead I let the system select all the positive invoices and then add the credit invoices to the installments which are "Not selected" initially. The installment page gets refreshed to to show unpaid amount as $ 150 ($300 - $50-$50-$50). However when I proceed to make payments the system picks $300 amount instead of  $150.