Hi Retreat,
Thank you for your post and welcome to the MYOB Community Forum, I hope you find plenty of useful information.
For BAS field being blank sounds like there is no Setup information on those fields. In this case, you would need to set up all fields and update after. Depending on how you're preparing your BAS (Manually or Online), depends on the process to set these fields up. Here are the support notes for this:
If you're Preparing Online: Prepare your activity statement online
If you're Preparing Manually: Prepare your activity statement manually
If you need further help, don't hesitate to start a new post and we'll be happy to assist.
Otherwise, if my response has answered your enquiry, please click "Accept as Solution" to assist other users find this information.
Cheers,
Shella