Yes, only civilian ships. In fact the ship itself(!) cant even transit. A 12kt commercial ship could make the jump with the help of this ship, but the other 25,700t ships could not.
I have tried adding engines in SM mode to no help (yes, I made sure they actually got trough to the ship itself, not jsut the design screen). Same with increasing the ship size to 30,000t. Same with new Jump-engines of higher efficiencies.
I dont get this, it should jump, should it not?