You need to go to setting on the Samsung health app, then select the 3 dots on top right, then select settings. Then scroll down to connected devices, then make sure the green dot is on for Strava, you will need to click it to turn it green., You will also need to sign up. Next scroll down to data permissions and select my fitness Pal. Make sure all the boxes where is says allowed to read are ticked and it should now work. Hope that helps.
I bought a gear sport watch and have managed to link s health and MFP, however, the steps linked are from my phones internal pedometer, Not the step count from my Samsung gear sport. I have selected Samsung tracker as an option for where MFP adds steps from but it is choosing S Health rather than the tracker steps.
This advice solved my issue with the syncing. Thanks!
Referring to this advice:
In Samsung Health, tap on the 3 Dots on the upper right side of your screen, click on SETTINGS, scroll down and click on DATA PERMISSIONS, click on MYFITNESSPAL, and make sure it and everything I wanted to sync between the two apps was turned on (it will be grey if off and green if on)