Update: I got things working with the command line xcrun iTMSTransporter instead of the App Store Transporter app. Maybe uploading metadata was never supported to work with the App Store Transporter app? If so, the documentation could be clearer, and App Store Transporter app should show an appropriate error. But, it seems like it does theoretically support it, it just has the bug with Bundle ID and SKU.

I have the same problem. I was unable to add Preview videos for days. It would just silently fail. No error or anything. There were no gray boxes in the Media Manager. The browser console did report a server error response of 409, but nothing useful (to me). I tried using the command-line tool xcrun iTMSTransporter to upload the Preview videos instead, and I finally got a more-descriptive error: Errors = [ERROR ITMS-10007: "There is another app preview upload already in progress. If you don't intend to make any app preview changes, remove the 'app_previews' element from your metadata.xml. To make changes, wait until the upload completes, do another lookupMetadata, and adjust the metadata.xml." at Software/SoftwareMetadata/SoftwareVersion/SoftwareVersionLanguageDetail/AppPreviewAssets] The key part being: There is another app preview upload already in progress. So, my theory based on this, was that Apple’s server thinks one of my previous App Preview uploads via the App Store Connect website is still in progress. Maybe it got terminated in some strange way? But, whatever happened, it looks like a zombie upload has locked my app’s data and that’s why I’m unable to add any new previews via the website or iTMSTransporter. I tried removing all previews and screenshots, then re-adding, to see if this would remove this lock, but it didn’t. Screenshots uploaded just fine again, but Previews were blocked. THEN… UPDATE Today, I tried uploading the iPad App Previews again and… it just worked! I guess someone fixed it or the zombie states on the server side cleared somehow? Anyway, there’s a new problem now! I set the Poster Frames on the newly uploaded iPad App Previews, which appeared to work ok. However, when I return to the Media Manager page, the Poster Frames were all black. I decided to just give up on setting Poster Frames and so tried to submit my app. But I got the error message everyone else here is getting: A few more items are needed in order to submit for review The items listed below are required for submission: There are still screenshot uploads in progress. It looks like the same zombie-upload problem, although now it’s for the Poster Frames (which I think is what the error is referring to, even though says “screenshot”). My guess some server code wasn’t able to finish setting the Poster Frame, crashed, and left it in a locked/zombie state again.

Update: I reported this to the Feedback Assistant too. Here's my link: https://feedbackassistant.apple.com/feedback/7791501

Nope. I've been stuck for 5 days now. I hope they're aware of the bug and are trying to fix it. Apple Engineers on this thread, any update?

OK, after spending literally a week dealing with this and not getting any useful responses from Apple, I managed to submit my app. Firstly, the bug appears to be twofold: There is no timeout on interrupted uploads. They’ll seemingly sit there forever, taking up one of your spots. As a Connect Engineer has stated in this thread, interrupted uploads should appear as gray boxes in Media Manager so you can delete them and re-upload, but I think there’s a race-condition bug where interrupted uploads plus new uploads can exceed the limit of 10 screenshots for a device. So, there are more than 10 on Apple’s servers, but the UI only shows a maximum of 10. If the gray boxes are in view — great! — you can delete them. If not, you’re screwed. (Side note: when you just drag and drop a whole bunch of screenshots for multiple devices into Media Manager the order always gets messed up eventually; they don’t follow the same filename sorting rules as Finder. So, you start madly dragging things into the correct order, right? I think this might be what triggers the race-condition bug.) Anyway, to work around this, while it’s still a problem: You need to delete every single screenshot and preview video. Once you’ve finished, they’ll start popping back! Some gray boxes, some things that look like the screenshots you just deleted. These seem to be the broken ones that exceeded the cap of 10 on Apple’s servers. Just keep on deleting. Refresh the page too. Then keep deleting, until every single piece of media has gone, and multiple page refreshes don’t bring any back. The problem now is how to you re-upload all your media without the same bug popping back. It's tough. I spent a day trying to use the command-line tool iTMSTransporter but even though my uploads were validated and reported as being successful, the media never made it into App Store Connect. There were no useful error messages. The only way I got it to work was by being CAREFUL. It literally took me 8 hours of trying to get it right. Here are some tips: Have custom images for every device and screen size? Start dropping what you can. Re-use device images where App Store Connect allows it. If you spent time making screenshot and App Previews for every device, this is super sad. But, you have to do everything you can to limit the number of things you upload. The more you upload, the more can go wrong. Only upload one device's media at a time. So, select all 10 screenshots, drag them in and wait for them all to upload. Then do the next. If *any* upload results in the screenshots jumping around and changing order, you've hit the bug. Go back again and delete every single item (as described above) and start over. Take care when swiping left and right to view all 10 images in Media Manager, if you swipe too far left while things are uploading, you'll trigger the browser's back function, which seems like it interrupts the uploads, leading to the bug. Upload App Preview videos last, one at a time. DO NOT SET THE POSTER IMAGE. This is very brittle and can trigger the bug. You just have to live with the default. I lost a week on this, it sucks. But, hopefully the guide will help someone on a tight timeline to navigate the bug.