Pastel Partner 18 - Customer Open Item History Report vs Match open item

SOLVED

Good day,

I have a problem that I can't resolve.  I have a customer that is up to date with all the payments.  But when I view the open item history report, it show that there are a few unpaid invoices.
When I investigate this by Match Open Item, there is nothing, and all the payments have been matched correctly.

What is the reason why this is happening, and how can I resolve it?


Kind regards,

Willem