I suspect there is a tax code on your payment which is not not displayed.
You have removed the bread crumbs from your screen captures so not easily verifiable.
If my guess was correct you could work around it by removing the account selection on the payment, which would reveal the tax code. If so delete it then re-select the accounts payable and supplier.
While I can not verify this is what you have done I can reproduce the behavior easily.
Create an invoice (tax code or not makes no difference
Open new payment
Select a tax code for the line item (it will be accepted and shown)
Select accounts payable for that line item (the selected tax code will be hidden)
Enter other data in the payment such as amount and save it
View screen shows tax code is still active just not shown on the edit screen
Hence my suggested work around in post #2
Which happens to be the same solution proposed by lubos in the thread he linked
If you goto the purchase invoice. I think you will find the full $1650 has been applied to it. Consistent with Lubos statement that the bug only effects the payment view screen display, not the actual accounting functionality.