A couple of blindly obvious suggestions, but they may give outcomes similar to what U describelll perhaps worth a few minutes to double check.
Gravity - I check your project’s gravity settings, and that the force is large enough to overcome normal gravity. You can swiftly throw some vast numbers there to test.
Target Location - Ensure that the root location of your grappling hook actor is where it should be. If it’s at the bottom of the rope or something. Again, you can move around the target location, to test this too.
State - Something might be changing the state prematurely, which would turn off the force.