The problem is with the graphing package. It really should be sandwiched, but the graphing function is somewhat brain dead and lumped everything together. There are a lot of other stuff that I'm not happy with the graphing (there's another post somewhere here that talked about this), but I won't be able to get to fixing it for a while. By the way, the graphing stuff is beyond my control. Everywhere else (i.e., the calendar, and list workouts page), the workout's time of day is respected.
This is the post you're referring to: Running Log Tip #1: Interval. Maybe it can help you. If not, let me know and I'll guide you through it.
It's a 5k. It hurt like hell...then I tried to pick it up. The end.