Brutal achievement doesn’t seem to complete.
Things that may help:
- name of the mission that isn’t counted as complete
- replay of that mission
If you practiced using cheats before the real thing, maybe you missed a reload to cancel their effect, and it caused that to prevent the mission to be validated?
@Undead
What about achievements that you DID receive but shouldn’t have? (I made a post about it in the bug forums under my name and got no response.)