Hi Acrylon,

If you edit the Control Payment for these invoices, you will see the maximum payment is zero. You need to edit the maximum payment to be the desired amount you want to pay.

If you ever partially pay an invoice, the maximum payment will be set to zero unless you set the Company Profile option to 'Set Amt Payable to Inv Balance' as enabled. The purpose is that if you partially pay an invoice, there might be a reason that you don't want to pay the remainder until you are ready. Enabling this option means that you typically will do partial payments without wanting to control the payment for the next time.