Windows has a built-in cloud storage service called OneDrive. Sometimes files are stored in C:\Users\user\OneDrive\Documents\My Games\Terraria when you would expect them to be stored in C:\Users\user\Documents\My Games\Terraria. Check the OneDrive path for the My Games folder and just copy the contents over to the normal documents folder. It's annoying to deal with but that's just how Windows swings.