I think the reason for the Exported FIT file to look like that is that Garmin isn’t able to handle RAMP steps? And fixed Power (eg: 80%) are converted to a +/-3w range…
Wow… it’s gonna be some amount of work to parse FIT files and get the app to be able to play nice. I wonder how Garmin is able to control Trainers using ERG mode w/ +/-3W Power Ranges… Likely it just sends the actual power target and uses the +/-3w for “out of power range” visual alerts.
When you export a workout as a fit file Intervals.icu uses ranges power for outdoor rides (no for indoor) and ranges for HR targets because it is hard to hit an exact HR number.