Elevation gain missing after uploading FIT file to Strava (Indoor Running)

Hi everyone,

I'm developing a custom indoor running app that connects to treadmills via Bluetooth FTMS.

The app records speed, distance, heart rate, incline, and calculates elevation gain based on the treadmill's actual incline.

The elevation gain is correctly calculated in the app and stored in the generated FIT file. However, when I upload the activity to Strava, the elevation gain always shows 0 m.

Here's an example from a recent workout:

• Distance: 3.27 km

• Duration: 18:57

• Calculated elevation gain: approximately 283 m

• Elevation gain displayed in Strava: 0 m

• Activity type: Run (not Treadmill)

I'm currently investigating whether the FIT file needs additional altitude-related fields or whether Strava ignores elevation data for indoor running activities.

My questions are:

1. Does Strava require specific FIT fields (altitude, enhanced_altitude, total_ascent) to display elevation gain?

2. Does Strava ignore elevation data from indoor running activities?

3. Would uploading the activity as VirtualRun instead of Run make any difference?

Has anyone experienced this issue with FIT files generated by third-party fitness apps?

Any help or technical guidance would be greatly appreciated!

Thanks!