Don’t know if it will fix your error but if you look into how UE creates the character for the third person cpp project they are not implementing
ASprintHealthTestCharacter::ASprintHealthTestCharacter(const FObjectInitializer& ObjectIntializer)
but
ASprintHealthTestCharacter::ASprintHealthTestCharacter()
on the make a multiplayer sprint,
you should look into how the jump is implemented
your current implementation will screw up player movement prediction,
to handle that correctly you will need to add sprint to your version of the UCharacterMovementComponent and into the FSavedMove_Character class
that’s the only tutorial on that topic that I have found so far