I got stuck in somewhat of a total trap the other day...
I was in my passenger Orca. Because these rewards are a thing, I had to fit a 4t cargo bay, which I'd rather not done.
So I took a load of missions, some of them with cargo rewards.
Then, upon undocking one of my passengers decided they wanted 3t of clothes. Rather alot for a short trip!
Anyhoo, one of my destination systems sold clothes, so I picked up 3t, and continued my tour of the galaxy.
Upon completion, I headed home to hand in the mission.
I could not hand it in, because I didn't have room for the cargo reward. Because it was being taken up by the 3t clothing....
Work that one out.
If we don't have room for the cargo reward, it should just be lost. (With a confirmation).
CMDR Cosmic Spacehead