Alright so I got lucky earlier to day and found a super dreadnought above a system near my capital. So I formed a fleet and went to go capture it using assault shuttle via command cruisers. I get there and after losing 10+ ships I finally capture except one problem. After I finish the engagement and move on to the next turn it's no where to be found. Not in the fleet that captured it, no in it's own fleet, it's jsut gone and I'm wondering. Where'd it go?

Maybe you accidentally scraped it or used it for research?

I figured it out, I didn't have xeno engineering yet but I thought I did woops.