I like survival, but often, around the 20,000 mark, one ship runs away. I use a pretty stationary fleet and usually, he gets away and stays away. The problem with this is that nothing spawns for a long time between waves unless all enimes are dead or like two or three minutes pass. It is a little irritating.
I have the same thing happen, but I wouldn’t blame the game for that. That’s what you get for not using engines. 
Put one long range missile in your fleet or add more fighters or fast frigates, lots of ways to get around it rather than sitting on the spot and complaining that your enemy isn’t moving to his death.
If you don’t want your ships to move away from each other use the escort or formation commands. I prefer the escort command as they will move off to engage things at ideal ranges but come back. The other option is to have no engines, this allows you to have more stuff… building tougher units… but it means you need to have ranged weapons or enemies will be sitting at 900+ pumping you full of missiles and plasma.
Yeah, it is engineless. So far, it is my best survival fleet at 50k, but I am having trouble getting it above that. Just read the fighter amour piercing thing… going try that today and the missile idea.