After completing an activity with a Garmin Edge, having it sync to the Apple Fitness and manually setting the effort (why doesn’t it sync also?!), if I open Garmin Connect again it will reset that effort to NULL again. It does this to all most recent activities (I believe ones completed during the current month) and I have to manually set the effort again.
This is a serious bug and should be fixed ASAP, since it makes the activities sync useless.
Sure there’s a work around by using a secondary app to do the sync, like Garmin -> Strava -> Apple Health, but that’s hardly a sustainable way to do it. Or what I have resorted doing: using the Apple Watch to record the activities and using the Edge only for routing / navigating. Pushing people away from Garmin devices is hardly what you want to be doing…
iPhone 15 Pro (latest iOS 18.5), Garmin Edge 540, latest Garmin Connect software and I can reproduce this bug every time I open the Garmin Connect app on the phone.