Anyway, I’ve got news. I fixed it adding an external antenna. Works great now. It took it for a ride and I get realtime speed on my watch. Never worked before.
I’m trying to find a way to post details on what it looks like. Maybe reddit or imgur.
The antenna is a tiny little patch antenna that I stuck to the inner plastic part of the controller housing. You do have to unsolder and remount a 0402 cap on the Bluetooth module to remove the internal antenna and use an external one. Not easy, need a really good soldering iron like a Metcal with fine tips.
Now I’m pretty sure its a signal strenght issue. Maybe it only affect some boards. Getting it reworked by onewheel customer service did not fix it. Maybe they replaced the module, but that was not enough.