Our April 2020 release included updates for both the Wave's firmware (version 42) and the app (version 1.5.1). While everyone gets automatically prompted to upgrade the firmware upon opening the app, this won't necessarily mean that the app has been upgraded as well.
If you have your apps set to update automatically, the app upgrade may have already been installed before you were prompted to download the firmware upgrade. (Click here to find out to check your current firmware and app versions!)
Hot Flash Mode was released with app version 1.5.1 on April 6, 2020.