You just need to stop that shift code running if you are crouched:
First Person Character can sprint while Crouched. Below you have some screenshots of the blueprints, i copied them from some good tutorials on Youtube. I’m a noob at UE4 and game development in general so i don’t know a single thing about Blueprints&Coding so if you guys have any screenshots for this please share them below because i would understand much better, but any help is appreciated : ) !