I've set this up fine on my fenix 6 solar, recipients get the start and finish messages, but if I request alerts based on time or distance during the event nothing is sent out. Strange thing is if I set it to send the update when I press lap it does work.
Got the latest software, in mobile range, as I said I can get alerts based on lap button but not time or distance.
Any ideas?
Fixed mine, worked fine yesterday, just removed my fenix from the app and then reinstalled it 
Thanks brother, that fixed it. :) One obvious thing that I see after removing the 6x from GCM and adding it back is in the Live Event Sharing section there is now a Transitions check box between Start and Finish check boxes showing up on the phone. This wasn't there before I removed and added it back...
It may have been there several months ago when it was working. but I'm more inclined to think it was a feature add but it defauted to unchecked and not shown in general until you re-tell GCM you have a compatible watch? Total guess just because it matches the symptons.
Regardless, that fixed it and that's what I needed. 
Yes I had the same appear, like you I think it was there a while back and disappeared, at least I know what to do in future. One word of warning, make sure the time/distance intervals are set right,
'm an idiot and had mine set at 2 mins instead of 20 mins, didn't realise until I'd finished my race after almost 2 hours and my wife asked why I was texting her updates so often 
