I thought it would exclude items already in my library. I was wrong. I'm not buying anything, but maybe GOG should fix this.

See Attachment.

So what does "Exclude Owned Products" mean then?

Where you don’t own the specific version eg Witcher 3 has goty, and the individual bits, and they have different ids, so some show as owned others show as not. It’s always been like this and won’t change.
My condolences on having cyberhoea in your library!

It's because Show all products is also selected as filter and precedes the Exclude one and simply lists all library. Delete that one and it should work.

GOG's store is annoying in that it shows you other editions and such as unowned, even if you own that exact content another way. It's especially frustrating when there's a sale for a favorite type of game... like CRPGs for me... and I have to sort through all the DLC and basic editions that show as unowned because I bought the complete edition.

As nightcrawler said though, this is likely never going to change because it's been this way for 14 years.

It works on my end, using Firefox (with NoScript and uBlock Origin). Did you try on a different browser? Or maybe clearing the cache/cookies will solve the issue.

I get the feeling some of you didn;t look at the attachment. This isn't the different edition problem... It is literally showing items marked as "in library" on the page with "Exclude owned products" checked.

I went straight on the Games Festival promo sale. However, it seems to be working now. It must have been a glitch in the system. It happens. Dunno why the topic is downvoted, it was more a joke than anything that games marked as "In Library" were showing with "Exclude owned products" ticked. I didn't manipulate it to be such, but there it is.

Ah, I see.
Yeah, if I go there, it shows all the boxes ticked AND it shows the games I own with the "in library" tag.
But, when I untick the box "Hide all owned products" once, and then tick it again - it works as intended.

Yeah, that was the funny part. Yesterday, that pic was after I unticked and reticked it. It took away some of the games, but still about half of the first 12 were in my library already with the box ticked (manually).