I did the “For the horde” run, where we killed all 4 needed bosses.
I got only 1 (Death to the King) out of 4 achievements, even though I got explicit honor points for killing the other bosses (needless to say, I didn’t get the For the horde achievement or the war bear).
I’m a resto druid so I didn’t attack the boss, only healed the raid.
The rest of the raid got the achievement (and the mount)
I have screenshots of the chat that I got the honor points which I submitted in a ticket to blizzard, who resolved the issues with sending me to search for a solution on wow head (!).