Hello charlie57,
Thanks for reaching out to us here. Glad to learn you're using QuickBooks to keep track of your income and expenses. The program is designed to help you save time so you can do the things that you enjoy the most. I'll be happy to share more info.
In order to locate the discrepancy, I suggest reconciling the account in question. Reconciling an account helps you pin-point the root cause of the discrepancy. I recommend getting in touch with an accounting professional for expert advice on how to proceed with recording the transaction accurately. You can get in touch with a professional using this link here. Otherwise, I recommend you to check out the following resource with more info about reconciling in QuickBooks:
Let m know if this info helps. I'll be one message away in case you have other