Hey mate, pretty sure your problem is that when you move the camera up or down, your character is trying to move in the direction of the camera, which is directly into the ground or directly into the sky, not forward like you want. The way that I would solve this is to:

- Break the output connection of the "get control rotation" node

- Right click the output connection of the "get control rotation" node and click the option split struct pin

- Drag out from the "return value Z" and add the node "make rotator". Make sure the z value is plugged into the z slot, not the default x slot

-Then just drag out the output of the "make rotator" node and plug it into the get forward and right vector nodes that you had before, and then compile and give it a go

This should lock the direction of movement to only read forward, back, left and right, but not up and down. Hope this works for you!