Hey Mario, I’m the dev who investigated this for you, and I’ve got bad news: you ran into a very obscure corner case that basically only affects this specific device.
I’ll try to explain it as best I can.
The IKEA remote uses something called Zigbee groups to notify the network about its button presses. The way this works is that the remote says, “Hey, join this group if you want to get notified when my buttons are pressed, and I’ll send a message to everyone in it.” So when we join an Ikea remote, we add our hub to the remote’s group, and store the address of that group in a table on the hub. If you’re interested, here’s the line in the code where this happens.
Now where we run into trouble is that our table for storing those groups has a max size of 32, so once we’ve reached 32 groups we can’t add any more. But where we run into even more trouble is that once we join a group, we don’t ever leave it, and we don’t expose the ability to leave groups to drivers.
This is for a number of reasons, namely that groups can affect multiple devices, and allowing one device to possibly influence the functionality of another device through its driver code is not something we want, as it leaves the door open for bad actors (or inadvertent mistakes). But the other reason is that we have access to a very limited amount of information about these groups, so we never really know if they’re safe to leave.
tl;dr: Over the lifespan of your hub, once you’ve joined an Ikea remote 32 times, future Ikea remotes will fail to report button presses. This is specific to Ikea remotes. Other Zigbee remotes don’t use this same mechanism.
The bad news: The only way to fix this currently would be to factory reset your hub and re-join all your devices, and after your 32nd join of an Ikea remote, you’d see the issue again.
The good news: We are working on an overhaul of Zigbee groups handling, and are currently thinking about the best way to handle your specific corner case. My team is pushing for this to be included in hub firmware v56, which would be the next one we work on.