I'm not sure if this is the right place to post this, because I don't know if this is a bug or a feature. I think my ship disappeared without any messages about it in the event log.
As you can see in the image, I had GSV Astrakhan 001 go through a jump point and discover a new system, then ordered it to go to Proxima Centauri-A I. After that I saved and closed the game. A couple days later I open the game and see that the ship is gone, you can see that its fleet is empty. Also, the design for the ship has disappeared from class design. The later orders you see in the event log is me trying to order the empty fleet. Maybe it got destroyed by an unknown enemy ship? Would I get any message then?
Edit: actually I remembered that I have a save before the jump, so I opened it and the ship is gone there too, so I guess the problem is that the ship did not save in the . db?