I have completed the achievement Heroic: Battle on the High Seas however, I was not given credit for the meta achievement Heroic: Pandaria Scenarios.
Do you have the other heroic scenarios done? you might be missing one.
Negative I’ve ran everything multiple times now. The only scenario that is greyed out for my meta achievement is Heroic: Battle on the High Seas.
Just to be sure, did you do the high seas scenario on an alt? You need to do all of them on one character to count towards the overall scenario achievement. On the Heroic: Pandaria Scenarios achievement, the high seas achievement will show as greyed out, but with a completion date when you hover over it (by the other character) if so.
No, I had completed all of them on the same MoP remix character.
This is definitely a bug. I also have credit for Heroic: Battle on the High Seas (earned 6/07/24) as well as credit for Heroic: Pandaria Scenarios (earned that same day). However, within the meta, Heroic: Battle on the High Seas is greyed out. Interestingly, if I hover over it, the tooltip shows it was completed on 6/07/24. My OCD hates this sort of thing.