I think you might be lost on the internet. You posted in a "User Community forum Basics" for a Professional Tax Preparer's group that uses Intuit's professional tax preparation programs. It doesn't seem you are using any of these programs, because you made no selection as to which program you are using.

I can give you some basic guidelines: the customer balances have nothing to do with your client's loan balance. You track and manage every loan individually, not relative to the other perspective. Second, Loans are neither AR nor AP. The Customer Loans payable to your client are a different asset. AR is a revolving short-term concept, that money is owed due to sales or delivery of goods and services. Lending to customers is a Long Term type of operation of Assets. The debt owed by your client is not AP. AP is debt owed for delivery of goods and services, not for debt balances owed from borrowing, and typically owed with interest. Debt owed is a different type of Liability, as long term.

I would never expect the Customer Balance total to match your Client's Balance total, except perhaps by coincidence. What you need to do is manage, reconcile and confirm each loan is being tracked properly, interest and fees are being tracked properly, etc.