Hey @ketillaxels
Please could you try the verify files option to see if this resolves your issue?
To do this, from your Steam Library section, right-click on the game and select Properties from the menu. Select the Local files tab and click the Verify integrity of game cache. If there is 1 file found every time you do this, don't worry, as this is quite normal, so it doesn't mean it is the cause of the issue.
If you continue to have the issue, please can you try uninstalling and reinstalling the game. If you can do so to a different drive, that would also be worth trying, but if not, just try creating a new folder to reinstall the game to.