I bought witcher series and install them.
Witcher 1 - successful (is in menu on left)

Witcher 2 - instalation failed due directx Command line switch error (it dissapear from left menu but it is in "my collection") instalation files removed itself,

Witcher 3 - instalation failed due directx Command line switch error (it dissapear from left menu but it is in "my collection") instalation files removed itself,

OS: WIn 10
Client GOG galaxy 1.2.10 (fresh instal)
GOG galaxy run as admin
Basic things like drivers/updates are done

So far i try download "Game backup copy" and instal

That sdk problem was something like "command line switch is not correct" or similar - after two try GOG show instalation failed due disk access (my kaspersky is off)

If someone know what to do let me know

EDIT1: The Witcher 3 Game backup copy was instaled without problem and synced with GOG galaxy.
So far so good

EDIT2: The Witcher 2 game backup is instalet but GOG reject to add it in menu . Even if i use "import folder" it say "no game found" but i already playing