RE: GP Bank Rec - Cash receipts, bank deposits and General Ledger
Welcome to the community,
In your case, since you have deposited the cash receipt (even in the proceeding month), you should have balanced Checkbook-GL balance up to date. Refer to the Checkbook balance inquiry to see your cash account versus bank balance. If they don't match, you may have an issue other than the above.
Banks versus general ledger variance is a common issue mostly caused by incorrect entry. You may refer to the following posts for further understanding;
Microsoft Dynamics GP Bank Rec out of balance to your GL?
Bank Reconciliation - Check book versus Cash Account Balance
To me, the best practice is to have one to one relationship (one checkbook versus one cash account), it does makes reconciliation much more easier. Furthermore, if you are on GP 2013, you can use the "Reconcile to GL" utility which generates a report for matched, potentially match and dis matched banks-gl transactions. The following post is expressive and useful
Dynamics GP Bank Reconcile to GL
Please never hesitate to share any further inquiry,