Just a thought here, it may or may not be related. Check the permissions and ownership of the folder in question as well as the files inside. Im on mobile currently or I would send you this myself, but you can google and find a quick reg edit that will add a "Take Ownership" option to your context menu. Use it to take ownership of the folder and see if it changes anything.
Also, does your user have administrative priveledges? And are you running the game/launcher elevated or no? Currently the launcher elevates automatically so that it can update games, and because of this, the game processes are also spawned as admin processes. Sometimes this can do weird stuff, and sometimes it actually doesnt happen, which again causes weird stuff (permissions). Its rare, but its a thing so I just thought I would mention it.