The option is greyed out.

It's only The Witcher 3. All the other games (including the first two) display as expected. I do not use Galaxy.


edit for precision

No problems hiding them here either maybe try the mystical powers of the account refresh see if that fixes it.

I invoke the Preterite clause. (Already did it. :)

The refresh link seems to have removed it from my library. The number on top of my profile is still 1 point lower that the number on my library.

EDIT: Link used from browser.

Where's the menu item for that, anyway? Or is it just some little "we have this nifty little secret url we pass along to people without a button"? It certainly worked for me, but i'd like to know how i should've gone about doing it without your link.
Contact support, but be careful. I actually have the GOTY version of TW3, but i also have the immovable object. Personally, i'm OK with it there. I use gogrepo, anyway, so i feel safer with the glitch there than with them potentially accidentally removing the copy i have getting confused.

EDIT: Attatching screenshot so people know we're not nuts.

I'm not particularly bothered. It's been there since it was added for free. (I haven't bought any of The Witcher games. I can't play them on my integrated graphics system.) I think the earlier games might have had the same problem, too, but now do not. As I said, I don't really care (I hide games in my catalogue that I can't or don't play.)

There is a product.isHidingDisabled variable so for some reason its on, or the browser is wrongly making it so, for some folk any web tech folk able to see a reason for that?

It is a hidden URL that often used to fix random bugs GOG have made.
Everytime you encountered some weird GOG bug, click the URL.
It also have another form:
https://www.gog.com/user/refresh

I don't think there is a button for it. But I wouldn't call it a secret either. With many problems it's the first thing that support or blues tell people to try. So the link has been posted on the forum about a million times by now.

Your screenshot is strange. It says that you don't own "The Witcher 3" basegame, which is probably the reason why you can't hide it. How did it get into your account?

The free DLC could be added to your account, even if you didn't have the main game, yet.

Basically, and this is probably the case for everyone else here, if you have the GOTY version, are not sure if there was somehow DLC missing from it, you clicked the free button and assumed it to just not take effect if you already had everything. In other words, 'cause GOTY and non-GOTY are considered different games for some reason. So i got DLC, but i didn't get the "other game." That's why i am being charged for it, even though i have an owned copy of the GOTY version right beside it (i actually unhid the GOTY version for the screenshot to show that).

I actually added the free DLC long before there even was a game of the year edition, when I was still waiting for a sale on the normal edition and its expansions.

Well, still, same thing, ultimately: the problem is that GOTY was treated as a separate game. To be fair, i can understand why: all that DLC would be a pain to install 1 by 1.