Hi Chad,
An invoice payment will post to your A/R account and to the Undeposited Funds or any asset accounts only. It will not post to your income account, unless you entered it as a deposit transaction.
You can check the journal to see the posting accounts of your transactions. Open the invoice or the invoice payment, click More and choose Transaction Journal.
You can also delete the invoice payment. Then, recreate it from the Invoice page by clicking on the Receive Payment button.
Let me know what you'll find out after checking the journals. Thanks.