Madrigal Debut Not Unlocking

If you are like me and the achievement Madrigal Debut, (Halo CE: Trigger a hidden music cue in Halo: CE.), is not unlocking for you despite you doing what is asked of you, I feel ya. This is not a sure fire way to make it unlock, and it's not very technical, but it's what worked for me/what lead up to me unlocking it.

First do what you're supposed to. Set the game to easy, run through Assault On The Control Room and stand on the correct spot shown in the video here:
If it does not unlock after that, what I did was enable the Acrophobia skull and just fly there. If it still isn't unlocking try to get to the spot shown in this video:
I could not for the life of me do it the legit way here, if you can nice, but I just flew there with the Acrophobia skull again. Your view will look like this:
This is on the first ledge past the third ring that has gear teeth. You need to be in the middle of one of the large parts of the ledge, just walk around and listen for the piano.

Now if it still did not pop the achievement like it didn't for me, you should try what I did. I save and quit, verified the game files and relaunched. As soon as I was in the main menu the achievement popped.

I know "verify your game's files" is a very basic thing to try but the reason I am even making this guide, my first bloody guide, is because everywhere I looked either said it's bugged or just showed how to get it but nothing was around telling people what to do if it didn't pop when they did the requirement.