I had a problem with importing a particular Apple Health workout into Strava. The workout was recorded on an Apple Watch SE and even though it showed up in Strava, upon clicking the Import
button, the loading spinner appeared but the workout never imported. I assume it was because I had turned on Low Power Mode
on my Apple Watch in the middle of the workout, which might have caused some issues with the data.
There are some free apps in the App Store that can export the Apple Health workout GPX file, but I found none that could export the heart rate data along with the workout.
There is an app called RunGap that can export the Apple Health workout with heart rate data, but it is a paid app and I didn't want to pay for it just for one workout.