If a client pays a deposit (no inv) before 28 Feb and invoice made out 01 March, the AR shouldshow customer balance in credit. This is not so and is a huge concern?

Hello, heather62. 

Thanks for reaching out here in the Community today. In QuickBooks, all the information the system receives is all dependent on what your Financial Institution shares with us.  

Continuous security updates, connectivity problems, and data transmission interruptions are possible reasons behind the unusual behavior. I recommend getting in touch with the Customer Care Team. They can pull up your account in a secure session and navigate your account to check the issue. You can refer to this link to contact our support team: QuickBooks Online Support.  

For your reference, you can visit this article for further guidance: Bank deposits.   

You can always go back to this thread if you have more questions about handling your customer's payments. Stay safe!