iMovie App Preview video "in wrong format" for iPad

iMove 10.1 OS X 10.11.1

I created a "New App Preview" in iMovie - I'm using a combination of screen capture/transitions and titles screens, but the first 0.1 is a clean, uncropped screen capture from iPad - that seemed to be an issue for others with this problem.

I'm only uploading the video for iPad, currently.

The video uploads and looks fine - I can set the Poster Frame - but when I go to save it, I get the following error:

I've followed the guidlines, it's a 28s video, the aspect ratio is correct etc. and the export settings are the default ones for exporting to the App Store. Could it be that I have to upload a video for ALL device types?!

The movie timeline looks like this:

and the export looks like this:

I spoke to an Apple rep on Nov 7 about this problem, and they confirmed it was a problem on their side and that many developers have been affected. Basically, all app previews are being rejected as "wrong format." No estimated time to a fix. Their recommendation was to just keep trying it…