Zwift were asking for feedback on Workout Menu recently - worth having a read. Quite a few requests/ideas for quick access to your favourite workouts, and include your custom ones in that list.
Quite a few other threads around about the Custom folder disappearing completely, or people bugged that it’s now been moved down the list making it a pain to find. Hopefully @Charlie_CC has seen those posts and is considering that with the re-vamp he is looking to undertake.
EDIT: Just looking at the new update and my Custom workouts are back to the top of list.