Actually, I like the way it works currently, and I believe it’s been designed to operate in that manner… (ie. not a bug!).
Why? I believe the ordering is intending to present the workouts to you based on their “proximity” to your current ability (your PL).
So: workouts with Levels >= to your PL (ie. those with Difficulties: Productive, Stretch, Breakthrough) are presented in ascending order of PL, while those with Levels below your PL (Difficulty: Achievable) are presented in descending order of PL.
Functionally, this makes sense, as the workouts that are most suitable for you (ie. having Levels nearer to your PL) display first and require the least (or no) amount of scrolling to discover.