I want to make sure you'll get an accurate explanation of why there are no records for August and September within QuickBooks Online (QBO).
If you're referring to missing transactions from the Banking page, we can manually update the bank account to refresh its connectivity with QBO. It helps us bring transactions that have not yet synced with QBO. Here's how:
Go to Banking on the left panel.
Within the Banking tab, select the Update at the upper-right corner.
If the same thing happens, import a bank file directly to QuickBooks Online through Web Connect. It's how to bring transactions when the bank account is not connected to QuickBooks yet. Log in to your bank's website and follow your bank’s instructions for how to download transactions for August and September. Once downloaded, save it where you can easily find it.
Then, proceed following the steps in Step 3, 4, 5, to review the file format before uploading them to QuickBooks: Manually upload transactions into QuickBooks Online. If you still encounter the same problem, please get in touch with our QuickBooks Customer Care Team. They can investigate this further with more tools.