I bought MCD a long time ago, and even switched PC, but after I reset my PC today, I cannot play MCD. I am sure I bought it on the website, and not the MS-store. When I log in, with the account I bought the game on, and add MCD:HE (the one I bought) to the cart and go to checkout, it says that I already own MCD.
I am not sure why this is happening, or how to reinstall MCD, so I looked through every relevant FAQ I could find, but they all say the same; if you bought it in the MS-store, you launch it from there, and not the official launcher, and vice versa.
Although I saw some talk about buying the game on the wrong account, but I have played the game before, even though the accounts are not the same, so I am not sure that that is the case either. 
I even have the receipt for the game, which is also attached to this thread.
I attached some screenshots for some "photo-evidence"