stray ship in fleet

And the ship type is what (maybe a colony ship that got mixed in with the movement orders).

Or a cruiser sized carrier. They hang back and launch their strike craft.

no its the first frigate you get. it just hangs out and i noticed when i run the mouse over it is that it is trying to jump to another system. i just stopped all orders and he stopped trying to jump to the next planet. maybe i miss-clicked or something

Yeah I noticed this as well. It seems to always be a light frigate. It acts like its trying to jump away but it never does.

Ive experienced the same problem, it goes off to the side as if it is going to make a jump and just hangs there. I gave it an order, once it completed that order it went back to its previous spot near the jump point.

I encounter this all the time and I have a theory. If you don't have your fleet set to all jump together, like when a new ship joins the fleet and you haven't right clicked the move button to add it to the "jump list", the new ship will jump to the new sector before the rest of the fleet. When it arrives, it realizes it is not with it's illustrious leader and sets its waypoint back to where the fleet was (but by this time the fleet is already enroute to where the lone ship is). For some reason the lone ship keeps its jump order but never actually acts on it. Definately a bug, but avoidable if you make sure the fleet is set to all jump together.

I 'lost' my Marza last night for brief time. I thought it was destroyed in the attack but discovered it had jumped into the grav well off to the side, far from the action.

This also happened to me, but I am yet unsure as to what causes this behaviour. At first I thought it was exactly because of what Riptorch mentioned, but then I noticed that the "stray" vessel had its waypoint set not only one jump back, but actually more jumps, going back to the gravity well in which it was produced. I think it is somehow related to the fact that the ship, when it came out of production, didn't actually make it to the shipyard's rally point before being ordered together with its newly auto-joined fleet to jump away. I say this because I noticed that it is always the last ship that came out of a shipyard that exhibits this behaviour, and of course the fact that it always wants to return to its "home" gravity well as soon as it has no orders queued. I find myself dealing with this bug or whatever it is pretty often, and found no way around it. Not even leaving the fleet then rejoining it seems to cancel that move order. The only way I managed to actually get rid of it was sending the ship back through all the jumps needed to get back "home", or downright scuttling it.

Actually, now that you mention it, Gehrschrein's observations seem more accurate than mine.

i now have to 'defleet' the errant ship, give it orders or stop all orders and then make it rejoin the fleet.

yeah iv seen it happen a few times it gets confused and just sits there

And did that actually make it stop doing what it did? In my case it made no difference, the ship still tried proudly to jump away.