Dynamics GP 10 introduced new, Excel based, functionality to reconcile AP to the GL (Dynamics GP-Tools-Routines-Financial-Reconcile to GL). Unfortunately, this doesn't seem to work correctly if there are outstanding transactions paid by credit card.
When you pay an AP transaction with a credit card, there's no GL affect, the liability within the AP subledger is simply moved from the original vendor to the credit card vendor. This seems to confuse the AP reconciliation process since there is no corresponding GL transaction for open credit card vendor.
To duplicate:
1) Start with AP balanced to GL (AP Aged Trial Bal with Options balances to GL Inquiry). Verify that Reconcile to GL shows that they match.
2) Enter an AP transaction via Transaction Entry and pay the voucher using a valid Credit Card in the system.
3) Post the transaction through the GL.
4) Run the AP to GL reconcile. The outstanding credit card transaction will show as not existing in GL. Since all step 2 did was transfer the liability from the vendor to the CC vendor, there shouldn't be a trx in the GL for the CC vendor. The GL didn't change. This functionality works right but AP Reconcile doesn't seem to take this into account.
5) Run the AP Aged TB with Options and GL Inquiry and you'll see that they are still balanced.
I've opened a case with MS to report this as a bug.