PSA: Be sure to check HR settings for device on Connect IQ app...

`Hmmm, I can't even seem to adjust HR zones through connect mobile... When changing the values they don't stick. Changing on the watch seems to work (after resetting there).

i haven't done an activity since changing them today, but there is a setting in connect mobile that need to disable auto max HR setting...

DEVICE (upper Right corner): User profile: Heart Rate and Power Zones ->  Auto Detection -> Max HR : OFF

It's disabled, but I still can't change the zones...

If I go to: User profile - Heart Rate and Power Zones -> Heartrate -> Sport Heartrate -> Running  -> Zones I see the 5 zones with their percentages. I can click on them and get the scroll option to change it but after pressing OK nothing is changed.

I noticed that the general Heart Rate and Power Zones -> Heartrate -> Zones DOES seem to work as expected (changing percentages there does work).

Ugh, screw you garmin. If you remove the option to set them on te webpage and point to the app, at least make it work!

that's very strange. i just tried it on mine: i changed z4 to 81% and it adjusts Z3 to 70-81% and it appears to have taken when i back out and sync with the watch. is there a way on the watch to confirm the zones?

btw, i just checked. my change of 80 -> 81% "took" when i look at my watch. not exactly sure what's going on in your case, but just wanted to provide you a data point that it's working for me.

Hmmm, that's weird...

And that's in the running specific zone? So not the general zone? And this is when changed in the watch itself? Or with the smartphone app (Android or iphone?)

Strange... Will give into it a bit more

so, to answer your questions... this is iPhone app Garmin Connect. when i changed he General Zones, it changed.

HOWEVER, today when i ran, i saw that my HR zones were all wrong (i finally got around to customizing my data field to use the nice HR with color meter). turns out (as you already know), i need to also set my Running specific zone. i changed it after my run (on my watch) during my walk cool down. let's hope they "stick" when i go for my next run in a couple of days.

it's giving me wonky Strava Relative Effort scores and ridiculously Recovery Times because the max HR is so far off. (i've been doing easy runs lately and rather than give me 20-25 hour recoveries, it's saying things like 50-75 hours)

Thanks for heads up OP.  The 955 definitely altered mine without warning and moved me from a 172 to 180max, which I don't believe is possible for me.  Not to mention in my case it takes me 5 points beyond most of the standard calculation methods that are based on a max HR value minus age x factor.   

All runs so fare have been "Unproductive"  SWEET!   I'm also wondering if the 955 just needs to keep on learning and it working backwards.  But that begs the question will it continually "auto calc" and become a moving target?

Future Enhancement Idea:  A nice feature add would be to prompt with confirmation before replacing HRmax like when a new lactate threshold is detected.

ha! i'm unproductive too! my V02max has been falling due to this problem (i think) but hopefully a few runs will right this trend. (t also says my training readiness is Poor.

i don't recall this sort of HRmax replacement happening on my prior transitions (735XT -> 935 -> 945LTE)

but i'm assuming that if you turn off autodetect, it won't be a moving target. it's odd that it thinks it can autodetect ones MaxHR after just one random run. seems a bit crazy.

Coming from a 645m, I was trending unproductive for a Month straight.  I actually began to worry about my health or if something was going on.  Just to be sure, I pulled out my old garmin HRM-Run chest strap and went our for a Lactate Threshold workout.  My Garmin is set to adjust HR zones based on my HRmax as a % of L-Threshold.  Low and behold, a new lower HRmax emerged and my runs were back to Productive, maintaining etc. 

What I think happened was it had been 4+ years since I last set my running max HR via % of L-Threshold.  Given that I've aged, I've been losing ground on my HRmax and I think it was time to do a downward adjustment (4 years = ~4 negative points).

My best guess is that if the 955 is now autocalcing and updating me to a higher HRmax, it would make sense that it views me as "Unproductive" simply because it doesn't think I'm working hard enough for the pace I'm running and considers them trash miles.

My plan:  I'll give the 955 a few more runs to see if it can dial me in.  If not, I'm going to turn off auto calc and put on the HRM-Run chest strap and let that set my max based on Threshold workout.