We have been testing the new Stream (on SharePoint) and have enabled cloud recordings (in Teams admin center). All our Teams recordings are now stored in SharePoint and playable in Stream (on SharePoint). We can also upload directly to a SharePoint site without problems.
But, if I visit the new Stream portal (http://stream.microsoft.com/) and click "Record" nothing happens. If we click "Upload" we get to pick a file but then it says "Failed to upload".
These functions are working in our other tenant but not the main tenant.
@aldenniklas1337 - Today the Camera and the upload from https://stream.office.com only uploads or creates in your ODB. If the user you are testing with doesn't have an ODB, I think you might see the failures like you are seeing. Is it possible you've not enabled ODB for that user?