I like most on here have had the issue with notifications for a while now since purchase of this watch ,( as can be seen in my forum posts !! ) A possible cause that Garmin software engineers might like to look into is that I have found the following to be helpful :
The issue occurs randomly for no reason , can be days without an issue or daily ! Not aware of an issue till I notice a notifiacation on my phone that hasn't gone off on the watch !
Tried all sorts of 'fixes' suggested on here , eg off/on with bluetooth , o/off flight mode , re-power watch/phone etc etc ; but today I think I have found out the main 'culprit ' - its possibly related somehow to the Garmin Golf app !?
The other day playing golf and after I checked on the phone app for scores , performance etc and immediately after the watch stopped notifications ! Force stopped all 3 Garmin apps and it worked again .
Today ( no golf just in work !) and the notifications stopped !! Force stopped the Connect app only and no joy , force stopped the Connect IQ app only and no joy , Force stopped the Garmin Golf app Oonly and hey presto the notifications worked again straight away !! Coincidence ? - I think not !!!
Please Garmin - look into this ASAP as this issue not being sorted is getting a joke now !!!