Currently, if you create a workout in Garmin Connect, you can only choose a workout name. While the list is very long, it's not exhaustive, and oftentimes you have to choose a janky "next-best" name for a workout (ie - instead of being able to enter "Romanian Deadlift," the only option available it "Single-Leg Romanian Deadlift with Dumbbell")
The other functions are great - being able to count and edit reps on my Fenix 5x, being able to hand-enter weights for each set, and tracking the data are all awesome.
