Hi
I have just upgraded to Windows 10. I had already manually downloaded The Witcher 3 full game, 1.22 patch and 1.22 Hearts of Stone, 16 free dlc and Blood and Wine through the GOG Galaxy app.

I installed all components of the game mentioned above but GOG only recognizes that the base game and 1.22 patch are installed.
If I go to Settings/DLC's installed, all boxes are unchecked. If I check the boxes GOG starts downloading the DLC's again even though if I start the game it shows all DLC's are already installed see attched pic
I have already selected Manage installation/verify repair and it still does not recognize that all the DLC's are already installed and still wants to re-downlaods them again.

Is there any way to make GOG Galaxy recognize that everything is installed and running correctly.
Thanks
Jaymes

EDIT
I resolved the problem by reinstalling GOG Galaxy then selecting 'Scan and Import folders' This then found all the DLC and saved me from re-downloading it.
Thanks

This issue is still happening with me though. Despite reinstalling GOG 3 times, it isn't detecting Blood and Wine. If anyone knows a fix, please do share it.

There's a setting in Galaxy, might be per game, that allows you to disable auto update.
You could try a repair afterwards, though it might start to download again.

I did try it. Blood and Wine still appears as not installed in GOG while I can play it fine in-game. I have automatic updates disabled (the game is still updated to 1.22 with 16 free DLCs, HoS and B&W installed), and verify/repair just queues a huge download.

Edit: even verify/repair isn't detecting B&W. Seems like I'll have to either redownload it through GOG or play with this issue.

I have automatic updates disabled as well. Sorry what worked for me isn't working for you. It is annoying that you have to re-download it. Hopefully it will be recognised and fixed at some point.