I mean if the animation before importing to Unreal shows the character flexing his legs and then straightening them that’s fine, but if it shows him also rising 20 feet into the air and then coming back down, then the jumping is actually in your animation data instead of the engine doing it, and my recommendation is to just keep his jumping motions of his body without actually translating the location of his body in the animation, and rather, have the engine move his Actor up and down.
My understanding of Root motion is that it moves the Actor in the World by the animation data translating the Root Bone of the character’s skeleton. So turning that off can resolve problems with animations moving the character around and up and down in the world when you don’t want it to.