i remember this was an option not in the bp graph but in the class settings / defaults if its a default controller.
something like “camera use control rotation yaw”
Edit: now i noticed i missunderstood you first.
you currently take the yaw rotation of the controller (so where the mouse is looking) then you tell the program to create a vector from this rotation wich will be fed into the movement. somewhere you tell the pawn to always rotate into the move direction - as a result, you character will only be running forward, the direction is “view yaw” ± “control direction” (- per wasd keys i guess)
i dont know your current setup of pawn/camera/controller
id take a look into the “first person template” and take a look at how its set up (controller movement and pawn and its camera)
theres a few things like control rotation/transform rules for camera and controller and how they relate to eachother.
Edit: 2nd hit on google when i search for “ue4 3rd person character no rotate”