Try browsing to the '..\Documents\Larian Studios' folder and renaming the 'Divinity Original Sin' subfolder.
This folder contains the saved games, configuration files and a level cache folder. Deleting or renaming it will get the game to recreate it on startup; playing the game from a different Windows user account would effectively do the same thing.
After that start the game, create a new profile and start a new game to check the hotbars. If that works, try copying some saves from your renamed folder to the newly created profile's savegame folder.
Didn't work
I also tried deleting and reinstalling the game. It seems the game is permanently broken for me until there is a fix for this.
