It is very boring to play challenge and it expired and you don't get any xp.

Answer 1

Well, that happens to all of us, some reasons:
- The XP loss is quite costy. When you're on a higher level, you will get +1 XP for a won and -31 XP for a lost challenge
- Many ppl are busy sometimes
- Some ppl don't want to be challenged with a particular weapon, but forgot to disabled it in their settings

Answer 2

I don't think so. That would lead to more people cheating with fake accounts and they would get xp for free.
Also, we get 1 xp for a win, it wouldn't be fair to gain 1 xp for a challenge you didn't actually win.

Answer 3

because I answer all questions right

Answer 4

but it should to get 1xp at least

Answer 5

you are right