Should work now. Will only work on Steam keys that were created before the release of the game, i.e. Alpha and Beta keys.
But what about my situation: I never have used any keys, but when on release day I have logged in profile at Larian Vault and discovered that Divinity: Original Sin Digital shows Steam instead of GOG, while I was absolutely sure that previously I had selected GOG (and checked that several times) and when
I wanted to change it - but after clicking on it (button with arrow, similar to change input button for Kickstarter Dragon Forum Badge) steam-key was generated and now it says Delivered and "This Steam key cannot be destroyed.". I am not using Steam at all and really don't want it. As I said I never ask for steam-key, wasn't use it and not gave it to anyone else.
How to solve this problem?