Sometimes customer, or their banks declare a payment as not correct, this happens specially with SEPA Mandates. This is called a dispute.

In the invoice overview, disputes are indicated with that status "Ongoing Dispute".

In the invoice detail view, there is a big notification on top, to remind you about an ongoing dispute. When clicking on "Respond" you are redirected to the payment provider where you can take care of the dispute and respond to it:

If you should lose a dispute, it will be indicated as following on top of the invoice detail page:

There are 2 dispute payment status that can be shown