Apple watch Series 3 and external heart rate monitor

Hi..

Just bought an Apple Watch 3 and sold my old Garmin Fenix 3 watch.

I'm using my watch for tracking excecises in the gym, and for my outdoor runs, and
found the build in HRM not usefull for training like that.

Then I bought the Wahoo Tickr HRM, and thougth that it would do the
trick 🙂..
For about a week now, i have tried to figure out how to pair and use the external
HRM insted of the internal one in the Apple Watch but without any luck!

What I am doing:

1. Activate the Wahoo Tickr (Parringmode)
2. Open Bluetooth settings in the Apple Watch.
3. Tapping the name of the Wahoo Tickr when it show up.
4. Wahoo Tckr is now connected.
5. Starting a outdoor run in the training app on the Apple Watch.
6. Observing that the green LED's is ligting up under the watch??
7. Confused and dont know if it is the internal or the external HRM that is doing the job??

Ok, then I try to deaktivate the internal HRM in the watch (Settings -> General -> training). As
written under this option, this does NOT deaktivate the external bluetooth connected devices!

1. Activate the Wahoo Tickr (Parringmode)
2. Open Bluetooth settings in the Apple Watch.
3. Tapping the name of the Wahoo Tickr when it show up.
4. Wahoo Tckr is now connected.
5. Starting a outdoor run in the training app on the Apple Watch.
6. Observing that the green LED's now is OFF.. 🙂
7. But..... Now the the heat rate BPM is missing in the training app??

I have tested the Wahoo Tickr HRM in other app's on my iPhone 7, and it is working fine. Of
course I remember to unpair the Tickr from the iPhone before trying to connect it to the Watch.

I also tried to disconnect the watch from the iPhone, but nothing helps!

Another thing i noticed is, that the Nike+ running app (watch and iPhone) dont show heart rate
at all as the only app! I dont care because I dont use Nike+. Just a information 😉.

Main reason i want to use the external HRM is that the build in HRM is making wird mesurings
when I am doing exercises. Most of the time it shows a way to low result like 55-65 BPM where
it should show something like 110-140 BPM. Most of the time it do not mesure anything, but that
is what I expect of a build in HRM like this.

Am I doing something totaly wrong here?? Hope some one can help and point me in the right
direction.

Regards
Michael.