If applicable, disable Steam cloud support either globally (in the client click on the Steam menu and select Settings, and then Cloud) or just for this game (in the library right click Divinity: Original Sin 2 and select Properties, then switch to the Updates tab and check the Steam Cloud section). Alternately, exit out of the Steam client, or Galaxy for GOG, and just start the game directly from the executable when required.
Next, try browsing to the '..\Documents\Larian Studios' folder and rename the 'Divinity Original Sin 2' subfolder. Deleting or renaming the folder will get the game to recreate it on startup; playing the game from a different Windows user account would effectively do the same thing. With Steam / Galaxy running and cloud support enabled, the client would just download the cloud copy of your existing profile. After that, start D:OS 2, create a new profile, exit and copy the saves from the renamed folder to the newly created profile's savegames folder, then test if recreating folder structure and configuration files makes a difference.
Also, it wouldn't hurt to start the Task Manager (Ctrl-Shift-Esc) after exiting the game, and make sure it is gone from the Applications tab.
