I got a reply back from Athom regarding the Symfonisk remote.
Seems there is a problem with Symfonisk Ikea firmware v.2.1.024. Luckily there is an update to v2.3.080 which worked for me!
The button presses are working and even turning the remote works. Not exactly the same as when connected to my Sonos via the Ikea Hub, but I suppose that to be Homey’s limitations.
That also explains why some devices are working in Homey, while others don’t.
So for everyone that has a Ikea Gateway/Hub; you might wanna update your remote’s firmware that way. You would have to re-add it in Homey afterwards and rebuild your flows (or have your go with @martijnpoppen’s amazing script: [HOW-TO][Pro][Cloud] - FIX flows after removing and adding devices)
Who wants to check Ikea updates: here’s the changelog for all Ikea Zigbee connected devices:
https://ww8.ikea.com/ikeahomesmart/releasenotes/releasenotes.html
