how to recreate bug/glitch
( use redstone ready preset to set this up quickly)

step one : create a one by one hole that goes 5 or more past height 31 downwards

step two go to almost the top

step three : hold shift to fly downward in the hole while touching a wall EDIT you dont need to be touching a wall

step 4 you will get stuck at height 31 (y 31)