There's apparently a couple of known issues they are working on, related to how the data gets uploaded to your DP, which is hosted on AWS. I recommend contacting your JAMF Buddy and having them add you to the list of people affected.
Yes, I have been having exact same issue since 9/2017.
Open the support ticket almost every month. JAMF aware of the problem and working on it, but there is no time line when it will get fixed.
I got following work around method from support. This method works for me most of time (Not always)
The work around is configuring the cloud distribution point as Master and upload packages via web browser.
If it is failing during an upload to the webapp specifically, what would give the best chance of success would be to attempt to re-upload that same package but with a different filename within that package record.