In my current game, I have several ship designs with movement in the 8-16 range (with hyperwarp engines. I have had some of these ships randomly have their movement reduced to 3 per turn, as though they had no engines installed. This persists even when I upgrade them to a different design. Then, some of these ships, several turns later, revert to the correct movement. There seems to be nothing I can do to make this happen. Has anyone else seen this?
