I can see my engine trails just fine. Borg, Aegis, Omega, and regular non-set engines.
(I'm using DX11 with all the video options turned as high as they can go)
The only engine trail issues i ever see are with the Aegis set, when there is a lot of background visuals. (like a random generated exploration map and there are lots of asteroids, and I'm going Full Impulse so my trail is long and very bright). The Aegis engine trail will flicker instead of staying solid in those situations. But that is unlikely to be related to the OP's issue.
How do you activate the impulse and warp trails. (I have the lowest posible video settings because i have a crappy computer but i see others impulse trails) Im a commander and i have efficient impulse engines.
Thanks. Any help is MUCHappriciated