Bug Report Ticket ID # 4,346,849
Federation Pilot ship engines used to animate when in combat, retracting towards the back of the ship and exposing the missile launchers for [Console - Universal - Microprojectile Barrage Launcher].
For examples of what the animation should look like, see:
Mercury -
https://www.youtube.com/watch?v=XXN3t8Ebe68
Icarus -
https://www.youtube.com/watch?v=mPCiwtdUAEo
Ajax -
https://www.youtube.com/watch?v=wNiybUaLl9E
Currently, this animation is not occurring as it should when the ships enter combat, nor when the Microprojectile Barrage Launcher is activated.
Chances are this is likely broken for the KDF and Romulan Ships as well, but I haven't had time to test them out yet, nor find video of their animations.
Edit: Here's a quick video I did of what is currently happening. Towards the end of the clip you can even hear the transfomation sound that would play when the impulse engines slid back into place.
https://youtu.be/mulRuJBiQyk