There is currently an issue with "A Simple Re-Quest". The achievement has a bug that will sometimes cause it to reset if you enter a Cross-Realm Battleground. We have a fix in place for this that will go live with patch 3.0.3 (soon). In the meantime, if you absolutely want this achievement, the best thing to do is to not enter a BG while working on it.

Many apologies.

Soonish?

As an update, there seem to be additional bugs with this particular achievement. 3.0.3 fixes some but not all. We'll continue to research a fix. Apologies once again.