Late Charges on fully paid invoice only

Hello

We have enabled Late Charges on Late Payments. I was under the impression that the Interest Invoice was only generated once the invoice was fully paid (either with one payment or with multiple payments).

However it turns out that the interest invoice is using the Late Payments as base to calcate interest.

Example

Invoice with Due Date  1/12/2018     EUR 5000

Receipt     1000  1/12/2018    (in time, so ignored)

                   1000  1/1/2019     late

                   1000  1/2/2019     late

                    1000  1/3/2019    late

Balance of the invoice is EUR 1000, I expected the invoice to be disregarded in the interest calculation until the final 1000 was paid. However an Interest Invoice was created to charge interest on the 3 late payments.