Thank you for providing me with detailed information about your issue today, @accounting234.
I'm here to explain to you the situation with the recurring transaction of your customer. Since your customer paid one of his invoices beyond the expected date of payment, this will reflect in the next invoice as a balance forwarded as paid.
I want you to know that you don't need to worry about this. This normally happens in recurring transactions when there's a paid past due before the next invoice.
Also, I understand your confusion about why it was the one reflected on the present invoice instead of the last one you created.
For example, your customer has an invoice last January 27 but has never paid it yet. Another invoice that was due on February 27 was paid on time. And later on, he decided to pay the January 27 invoice on March 10 so this will be considered past due but paid.
So, when the next invoice is generated on March 27, the last customer payment dated March 10 for an invoice past due on January 27 will reflect as a forwarded balance instead of the February 27 invoice.
However, for the April 27 invoice, it will be back to its recurring cycle. This also means we'll need to let your client click the "View details" to see the correct amount.
On the other hand, if your other clients are experiencing that issue without having a past due, I'll recommend contacting QuickBooks Online support again. They can help you pull up your account, check out the root cause of it, and find the best solution to fix it.
You might want to get the list of all your recurring transactions and the accounts they're linked to in QBO, you can read this article: Review your recurring transactions in QuickBooks Online.
For additional questions about managing your recurring transactions, never hesitate to reply to this post. I'll be happy to extend a hand. Keep safe and have a blissful day!