I've started to get the same problem since the beginning of August. Haven't got any problem in the past, but now I just cant sync from Strava to SHealth or from SHealth to Strava.
Mne is the same as well. Hasn't synchronised with for a good 1.5 months now. I had a similar period then it started synchronising randomly once a week but nothing now for a long time.
All my settings are correct as used to be fine.
Big post over on Strava forums about this also.
My sync between Strava and Samsung Health stops every now and then so I have to go into the Samsung Health app on my phone and other Settings click on Connected Services and turn Strava back on (green dot).
15 may 2020
Yes mine was working earlier this week and has done so for last 3 months but today doesn't hopefully it's a server issue and will post itself