Same problem. No ability to capture stream with the Microsoft Store app in Windows 10. This is seemingly exclusive to Windows 10.

For Applian support staff to test: You'll need a Windows 10 computer, open the Windows Store app and watch a free movie trailer. The trailer is opened directly in the Windows Store app (not in a browser window, and there's no link to get it into a browser window). I've tried capturing the stream with RMC6, when a movie was playing in the Windows Store app, also with a trailer, and RMC6 apparently doesn't see either stream because nothing is recorded when RMC6 is in the auto capture mode.