I’m not sure if this is by design or if it’s a bug. I did this workout on Zwift and did some freeriding to warm up prior to starting the workout. At the end of my free ride, I was close to a 30-40 second sprint segment so I decided to go for the sprint and then spin a little more before starting the workout. As you can see from the screenshot, both threshold and anaerobic workout levels got massive jumps. I’ve never seen jumps this large before so I’m reporting it in case it is a bug. If it helps, please feel free to look at my workout history and discuss it publicly.
I’ve had this happen to me. It’s your sprint that caused it. Submit a ticket, and TR support will easily sort it out.
Those levels are useful for you to analyze your data and compare it to other rides/workouts, but they really aren’t used like they used to be behind the scenes.
Instead, we simply look at your recent power curve to determine what workouts are best for you.
If your upcoming workouts didn’t shift substantially because of this, then I don’t think there’s much of an issue here. 