Hello,
I’m attempting to submit my second asset to the Asset Store and for some reason the new Package Uploader won’t get my package information from my account. I logged in correctly. It does this brief downloading action then the window is empty. The only option I have is to close the window.
Has anyone else run into this? Kills me, I’ve spent a long time on this asset too!
I’m currently experiencing issues with uploading a new project as well. My issue is a different issue than yours (my “upload” button doesn’t work), but they’re probably related. I hope there will be a fix for all this soon, as it’s extremely frustrating to work on something and get it all ready only to be failing at the last step and have it be out of your control. 
I eventually fixed by problem. It was due to the fact that they switched the store page setting over to a web based system. You create the draft of the store page in your publisher page, then you make the package in Unity and upload it onto that draft page, and then publish it from the web. It’s a little weird. They need to make some video tutorials.
The new system is better I think, it just takes a little bit to get used to it. Well I should say that it’s “better” when it’s working. But right now the upload isn’t working for me and a number of other people.