Interface Variables Don't Sync Across Blueprints

Quickly, to explain, I’m trying to make a global Boolean called “In Menu” and access it in other blueprints for a branch true or false statement. So I tried this “game instance technique” out and created a game instance blueprint and inside of it I made a variable. I then tried to access it in my widget blueprint by casting to the game instance and the object wildcard was get game instance. This didn’t work shown by the fact I had a print string hooked up to the cast failed node. Why?