I Had the same issue where I registered everything and then the connection to the ATO failed with the error.

I rang the tax office and they said oh yes you can put a branch number of 001 in but as to where on your software we do not know.  There is a section in the payrol settings to enter a branch number but not for GST settings or in general settings.

I never knew I had a branch number as I dont have branches. Its juts me and my small business with three staff.   Surely this means that no Quickbooks online customers can submit their BAS online at the moment.

And I dont think we can do it by paper anymore either with all the changs to AUskey and so forth. 

Can you get this fixed ASAP  please. You'll probably be costing my staff from getting JOB KEEPER because I cannot submit anything and there are deadlines which I've now missed.  They can starve obviously.

What to do?  When the connection error suggests I need branch number and I cannot put one in place for the connection to work.