I have all of my task groups set to auto refuel when they are at 30% or less fuel, but despite that, my lone gravitational survey vessel decided to fly around until it ran out of gas. I'm only on my 2nd year in my current game, so I know I'm not out of fuel, and in fact, it's sister survey group (The geo one) went back and tanked up just fine (Actually, during the same turn even). What else would cause something like this?