Tried this some minutes ago, the marketplace content is lost.
Used my MS Account with Game Pass and now with Steam, but my Content is “rebuyable” and not downloaded.
Wow, seriously? I kind of expected that by the way the entire thing was released, but was hoping for not. What a bummer, I will skip the marketplace. I got KDEN directly from FlightBeam and they use a 3rd party content manager. Thanks for testing for us!!