We did 28 uploads for the PMV 300 visa (18 Applicant and 10 Sponsor)
Then another 18 for the 820 application (4 of those were the Form 80 split into 4 jpgs of multiple pages)
The good news was that the 820 was granted about an hour after I uploaded the Form 80.
If you reply to the email request, for the Form 80, and tell them you have uploaded it into the sponsor section, it should be OK.