this is a fairly common mistake I have made some time ago. Transitions will only work if you actually set a height. Try to set the height to 0px an dthen on click of a button to 100px, the transition should work. If you do something like height 0px to height auto, it will not work.

If you need a dynamic height, best way is to get Element inside the height cointainer and extract height dynamically.

Good luck!