On a wipe IAT said that Dirtflap's Revenge's criteria as being me when two pillars were up.

The achievement text was still red.

Note: There are some odd things going on with this fight.

For this achievement, I'm just using Blizzard API to tell me when achievement complete so not quite sure why it reporting completion incorrectly, especially when the UI is still reporting it incomplete. I wonder as the fight was not working correctly, whether than could be the cause. Will keep on the radar and test if/when the fight is fixed and see if that resolves the issue. Thanks for reporting though