I'll help you fix this, Prosperbk.

When customers have no outstanding balances or overdue invoices, the transactions will show up in the Statements unavailable.

Here's a sample screenshot for reference:

Since this is not the case from your end, we can do some troubleshooting steps to get those customer transactions transferred over to the Statements Available section.

Here's how:

1. Open a private browser or incognito mode, and log in to your QuickBooks Online account. Private browser doesn't store cache.
2. Try to open a new tab. If it works, go back to your regular browser and clear the cache.
3. You can also use other supported browsers as an alternate solution.

You can also read this article for more information about statements in QuickBooks Online: Create and send customer statements in QuickBooks Online.

Please reply to this post letting me know how it goes. I want to make sure this is resolved for you. Thanks!