Did anyone who had to return their fleet today notice not all fleets return with fuel ?

I wanted to do the Tony Montana quest, but 1/3 of the way I changed my mind and returned the fleet.
I didn't pay attention at that time, but when I got the report in my inbox, I saw the lack of returned vespene:



The fleet reported a consumption of around 900k vespene, so I sent it at 20% speed ( 400k vesp ). First I thought this was the reason nothing was returned, but then, the next thing happened:

An hour ago, I went after two pirates, sending 1 fleet of cruisers ahead and 1 fleet of recyclers for each of them. When they were at about 70% of the way, someone else reached the pirates, so I had to turn back.
Only one out of three returned with vespene:



You can see that each fleet of cruisers was paired with a recycler one, and both pairs were returned at the same time.

How does this work? You get leftover fuel arbitrarily? 

some ships have "warm up time" the formula for that can be easily found by clicking "warm up time" on the description page,
what is this warm up thing?,a ship doesnt not go full speed until a certain period of time passes,
why?if you recall a ship before it starts going full speed,you get 90% of fuel,IF the units passed the warm up time,then calling them back will result in loss of fuel.

why recyclers returned with fuel;and cruisers didnt?simple warm up time varries from a unit to another...recs warm up was still not over...while cruisers were full speed when you recalled,so you got fuel from recs,but  nothing from the cruisers

i hope it's clear

yep warmup

very useful, chicken... very, very much...

Good job SCloud! For real! :D

One recycler returned with fuel, the other didn't :) Bottom of image, right above the "Share fleet" icon. First recycler has gas, last doesn't.

And usually, in the past, when I returned attack fleet ( battlecruisers, destroyers, etc ) they came back with fuel. I don't have screenshots for that, but I'll keep an eye on that from now on.

excuse me khaldun i was just agreeing with scloud and did not feel the need to repeat everything he said so i just backed up his comment by saying "yes warmup"!
there is not need for moronic sarcasm
quote "sarcasm the recourse of a feeble mind" dr smith lost in space
 

why destroyer attack on allied ships

it does not it boost the mechanicall ships dmg

Aw don't be all upset chicken :P
Sarcasm is an art. And art should comfort the disturbed and disturb the comforted. Seem you had a bit too much comfort,hm?
Anyway... really, don't be upset. I usually like your commentary. You often help out and say things which is needed to be said. You're a good egg.

If you cancel the flight before warmup time is passed, you will get back 90% of fuel spent.
It is not a bug.