Character Sprint prblems

Hello,
I made a basic sprinting script in the Standard Character blueprint, but i have some problems with it.

Here is the script:

When my character sprints it looks like he is setting the speed constantly, once to walking speed once to sprinting speed. As if there was something that set the speed back every tick. Does someone know how to fix this or what causes it?

I’m having trouble replicating this. I created a fresh Third Person BP project and added your script to the MyCharacter BP after adding a sprint input action to the project settings.

Is this a fresh project you’re working with, or something that’s already been worked on a bit?

Have you tried with other inputs?

It is a project I worked on for a while, but I have changed nothing regarding the character movement or input settings. Btw I am working with 4.5

Edit~ I ran the game on a dedicated server, and the client had the speed changed but server still had it at the old speed, the configuration in the Image shows the easy fix for it:

Is this fix safe against potential cheaters?