Supersonic achievement wont unlock

The supersonic trophy/achievement wont unlock for me. I traveled to the end and got the elytra, then in the over world i dug a 1 by 1 hole that goes all the way down to bedrock, built a tower to max build height and flew strait down into the hole. There is no way i wasn't going fast enough but after attempting this roughly 10 times with different configurations, including having 1 by 1 rings going all the way down my tower i still can't unlock the acheivment. I even looked up guides online to make sure i was doing it correctly. i know i can unlock acheivements on this world because ive gotten several other achievements even within the last few hours.