First Gen HRM-Run drops out after 2-ish mins

a similar problem with data loss after 2.08 minutes and with firmware 3.21 beta https://connect.garmin.com/modern/activity/2831839386

Same issue with my fenix 5x +, HR works fine, but vertical ratio and GCT drops out exactly at 2.01mins into my run. Its happened twice and both times the dynamics screens disappear as well. I'm running the 3.10 firmware. I know it's not the HRM as I literally used my Fenix 5x 2 days prior to my 5x+. I'd be thinking it's firmware fix.

Further development: this morning, instead of "Trail Run" I had a "Run" and all was peachy again. RD data for an hour, no interruptions. Will do a Train Run over the weekend to see if the "mud" is stuck in that activity especially or now cleansed from the watch completely...

Trail run was a drop so was a "Run" yesterday. Today I tried with "Disconnect phone" and voilà: we have RD...

Today i disabled bluetooth on the Fenix, instead of disabling on the iphone.Running Dynamics were recorded perfect. No dropouts at all. But i need to have lifetrack running due to health issues, so this time I used a vivosport band for livetracking in parallel to the Fenix. This can only be a temporary fix. Garmin needs to work on their code. Any official news around. Can someone from Garmin confirm they are working on it like mentionend a few posts before.

I upgraded my Fenix5 to 5plus 2 week ago and I've run with it since (4 times a week). I did a Lactate Threshold test that failed and I didn´t know why. Then I discovered that my running dynamics where missing in all the activities (I use a last gen HRM-Tri, battery new). Then I did some research and tried the solution of removing the HRM-tri from the watch, then removing the battery from the strap (and then re-installing it again). I did a short walk in "Run Mode" with my strap and the problem wasn´t there so I thought that it was solved. But today I tried for a real run and it happened again, at 2:08 as you all (I hadn't realized earlier that it was always the same).
So I've contacted with Garmin afterward. They told me to reset to factory settings the Fenix and wait if it solves the problem. But as I read you (I hadn't read you before) I began to understand that its a problem of the firmware. So I've just called again to garmin, and now a different person tells me that there is already an "open incidence" and that it is a firmware issue and that they are working to solve it. So, for me, so much time spent trying, looking....for nothing.
I'm not very happy with Garmin right now but it seems that writing this down soothes me a little.

Nevertheless I will try tomorrow the bluetooth off solution, on my iPhone if I understood it right.

I hope we'll get it soon, and will keep on reading this thread in case anyone finds another solution.

+1 I have the same issue with my 5 plus and HR-TRI (at 2:09 mm:ss)
Not a battery issue - HRM works without problems on bicycle rides (watch placed on handlebar)

I've just come back from today's run. I turned off the blue tooth of both the Fenix5+ and the Iphone. It worked flawlessly! I'll run again on Friday and I'll try with the iPhone’s blue tooth on so I can listen some music.

Trail run was a drop so was a "Run" yesterday. Today I tried with "Disconnect phone" and voilà: we have RD...

This seems to be the generic solution now in any run mode. Disconnect phone in Quick Menu and RD is full on.

I'm having the same problem. Fenix 5 plus sapphire with HRM Run. Two runs so far, and bothe times the running dynamics drop out after about 2 minutes. I have also noticed that the heart rate drops out and then comes back. I imagine that this is a shift to using the wrist sensor.