Currently on v14.40, but I believe I experienced this with previous versions.
I have a Z2 HR range alert set for my Trail Run activity, and I have vibration ON and alert tone set to 'During Activity'. I aim for the upper end threshold during my runs so I tend to trigger a lot of alerts as I exceed the range by a few beats then get back into the desired zone. When I exceed the range I always get the tone/vibration alert, and I will get the reoccurring alert if I stay there longer (I think it's every 30 seconds). However, when I move back into the desired zone I will only occasionally get an tone/vibration letting me know. If I look out for it I will see the 'In Desired Zone' screen pop up, just no tone/vibration feedback.
I haven't had the watch long, but I recall when first using the alerts it would work as expected. But then I started noticing the 'In Desired Zone' tones/vibrations were sporadic. I restarted the watch before one run and it seemed to improve but I still wasn't getting all the alerts over the course of the run. Yesterday I completed a run and didn't get a single 'In Desired Zone' tone/vibration.
Restarting the watch is the only troubleshooting I've done so far. But I wanted to see if anyone else has experienced this before I spend more time trying to figure out why this is happening (e.g. different activities, different zones, etc).
Thanks!