I refunded Fallout 4 last year when it didn't work as I was going to use it with Fallout London. Decided to use my Steam copy which was a bit more difficult to get working, but anyways the copy of the game was on my GOG account for months and I wondered what was going on. I went on a Reddit thread about someone having the same issue and there was a link I clicked on and it's been removed! What's weird though is if I go to Fallout 4 on the store it still says it's in my library when it isn't! I think I'll contact support as it appears to be a bug.