The patch notes for 25.0 contain the following item:
- [Mercenaries] Fixed a bug where completing a Heroic Bounty would not count for Tasks requiring a Normal Bounty completion.
However, I just completed the heroic Plaguemaw the Rotting bounty with the following task on my desktop: Complete the Plaguemaw the Rotting (Normal) bounty in the Barrens. Party Includes: Vanndar, Lokholar. This was for visitor Chi-Ji. My team was Lokholar, Vanndar, Ysera, Murky, Chi-Ji, Hooktusk. So I included the 3 mercenaries I was supposed to and completed the bounty in heroic, which is supposed to be possible under patch 25.0, yet I got no credit for the task.