Hi Jeremy - In workout mode the terrain is set essentially to 1%, so it doesn’t matter weather you are going uphill or downhill, the resistance will all feel the same. If you’re often finding that higher wattage targets are too high in ERG mode and haven’t taken an FTP test yet or recently, we highly recommend that. It is also worth nothing that some of the Zwift Academy workouts have really really high wattage targets in order to help us identify talent and scout finalists.
While in workout mode, you can use the Zwift Mobile Link app to adjust your FTP up or down by 10%. If you feel like a particular workout is exceptionally challenging or if you’re feeling extra strong one day, it’s a great feature to take advantage of.
I’d also love to point you to this article - https://support.zwift.com/hc/en-us/articles/209980783–How-to-use-ERG-mode-in-Workouts - This will explain what you’re feeling, why your trainer is locking up and how to avoid that.
If you feel like your trainer is having issues other than described in that article, please open a support ticket. We’ll gather some more info and work with you on some troubleshooting steps to improve your next workout.