So I set up a Niagara System spawning Decals via the Decal renderer to create Skidmarks behind a car. This works perfectly fine even in sequencer when I playback the Car driving with the Niagara System parented underneath to leave the Skidmarks as a trail.
The problem is if I want to render a still image and set the Niagara System Life Cycle to Desired Age as I would for Particles, Meshes or Ribbons to stay in place the Decals wont. They will continue the same behaviour as before so they despawn after a couple of seconds as their lifetime seems to go on.