Q: The payment we received was for two invoices, so my understanding is that payment gets split then I should be able to select the appropriate invoice for each payment in the split but the checkboxes are all grayed out and I can't select anything. There are no icons next to the split amounts in the transaction record, only next to the payment...

A: What happened was that you used the split function previously to “split” the amount without selecting invoices, and the remaining balance of this transaction was 0. Because the remaining balance was 0, you are not able to select any more invoice (no amount left for you to match). What I did was to go to each of your split row in the pop up, zero out the balance, and then re-select the invoice link, this will enable the invoice checkbox to be “clickable”, as the remaining balance now is > 0.