This is reminiscent of a problem discussed in a previous thread, Signia Charge &Go AX Nx 7 with Streamline Mic Bluetooth. In this thread, it came to light that the only way to clear the blue tooth pairing from the HA’s was with the Connexx software. And when that was done and the Mic re-paired, the situation was resolved. It could be the same for the IX’s as well.
Edit: Ha! I see you’re familiar with that thread, Liviu, so you’ve probably tried removing the pairing using the software. Oh well, maybe the post will benefit someone else. I am disturbed by your post, though, as I was thinking about updating my firmware to take advantage of some of the new changes, but, now, I’m a bit reluctant.