I'll add on my S2 prob here too...95% of my calendar events don't sync to the Gear. Using Note 5 and Gear S2 3G (Verizon for both)
I have updated both phone and watch, did a light reset and hard reset on watch, installed and uninstalled Gear manager, paired and unpaired device two or three times, even had Samsung try to do support on it mobile, but they quite literally gave up after taking about three hours of my time (kudos to them though for sticking with it that long!) after not really suggesting anything I hadn't already tried or considered.
Now it's to the point where I either have to send it in to Samsung (where they said they would charge for the repair if they found any damage on it... kind of out of my control once the device is in the mail), or drive forty miles to LA to see if Samsung support can fix it in person, which honestly I don't have the time for.
Before I resort to either of these, do any of you brilliant fellow Samsung users have any advice or tips that you can recommend? I'll still search through other threads in the forum to see if there's similar threads, but so far I have yet to find this issue. Thanks in advance!