https://support.strava.com/hc/en-us/articles/35028940753165-Power-and-Cadence-Data-from-Apple-Health
This was an issue for me early on in my power meter days. You could get this to work but would need middle man apps to pull from Apple health and push to Strava. Now things work natively when recording via iOS fitness app.
I know a lot of folks rely on Strava as the data broker for services like TR. I’d still like to see a direct integration between TR and Apple health to remove reliance on Strava.