No rewards from Spy sorties?

[Sannidor]

I'm not greedy but I feel it has never been really explained why Spy Sorties do not drop extra rewards identified at the end of mission, like Nightmare or Syndicate?

If it's a bug it surely should be fixed. 

If not, it kinda makes Sortie Spy missions weird - I don't bother to stay undetected, just brute force and run since there's nothing to reward stealth.