@zucchero so I tried the Di2 S+ App today.
I’m using Ultegra 12-speed Di2 groupset and I did get it to work.
First I tried to put the Di2 system into discovery mode as you did. And similar to you then the S+ app on the watch could not find the Di2 system.
I then “woke” up the Di2 system by doing some shifting and then tried the S+ app again and this time the S+ app found the Di2 system. I’m still not sure what is the correct way to make the connection.
Funnily enough after the ride (130km, 5h 40min), the watch synchronized with the Suunto App right away. I haven’t been able to get syncing working right away for many weeks since the infamous sync bug was introduced. But this is probably just a coincidence.
There seems to be a bug either in the Di2 S+ app or in the Suunto App when displaying the information.
Below are two images from the Suunto App showing the front derailleur shifting and the rear derailleur shifting overlaid on the altitude.
Screenshot_20240505-214802.png
Screenshot_20240505-214819.png
After around 3 hours, the shifting information seems to stop.
Will I be using this S+ app? No, there are no statistics in the Suunto App regarding the gear usage which was what I was expecting (I already have real-time Di2 gear info on my cycling computer).
About the bug: Maybe something @Raimo-Järvi could have a look at?