Hi there,
If you're not seeing the September 2024 BAS period in your To-do list, it is that you've already marked it as lodged in QuickBooks Online.
Let's click on the History tab in the GST center to see previously lodged BAS. If the issue remains, I recommend signing out and sign back in to your QBO account or contact support to better help you with your BAS.
You can check this link for reference on how to: Lodge your BAs or IAS in QuickBooks Online.
Post again in the Community if you have further BAS concerns.