AP invoice closed out, but still has a value in the Balance field.

Has anyone ever seen an invoice that was paid/closed, but still has a balance? we have a weird situation with an AP voucher that was paid via wire(manual payment). On the payment side (via insight query), everything looks fine. it's applied to multiple vouchers, which is pretty normal, and hit all of those correctly except for this one. However, if you look on the voucher side, and preview the voucher applications, the payment shows with $0 value, and the invoice is still showing a Balance. I'm wondering if it was some kind of posting error the needs to be corrected via SQL? it's always preferable to do it via the UI, but i'm not seeing any way to change anything on either the payment or the invoice.