Same Here, but at first I assumed Zwave problems thats why I reassigned (exclude, factory reset, include) two switches.
These two are working with the new Test release so far.
Today I have tested the other single mode switches.
IT seem they are working fine when the assigned devices i set to “other” instead of “lamp”
Will report this to my Athom ticket.
My double channel switch is behaving as you describe, even when assignment is set to Other
Same situation in my Homey 
I have around 15 Walli Switches, some configured as single and some as double switches. I find pretty much all combinations of working and non-workings switches: some singles work, some don‘t, some double switches channel 1 works, some don‘t. Only consistent point seems to be the second channel never works giving the error missing capabilities listener: onoff.output2. Another difference to what you have reported is that some of the wall switches give timeout errors … but respond quickly, when I test them on the Homey Developer Z-Wave page.
Any solution would be greatly appreciated, I don‘t want to desctroy all my flows when I remove them.
I’m guessing you haven’t installed the test versions of the Homey Fibaro app yet, right?
In my opinion, the error with the message “missing capabilities listener: onoff.output2” should actually have been fixed by now.
If you want a solution without having to remove and re-add the devices, you’ll have to wait for an updated version of the Homey Fibaro app.
Therefore, I suggest that you report the issues you’ve identified to Athom Support, even though many users have already opened support tickets regarding these issues.
I do not belive it
Athom released a new Test Version 3.8.14 and the Single Mode ist broken again.
Same Error as before.
Yep, I can confirm that. 
Support says they assume all should be fixed.
It seems to me, that they are not able to merge all fixes in one combined release?
To all having the same problem, please open tickets to get that fixed with priority
The following test version was released:
Version 3.8.15 — Fixed bug in multichannel association removal
Now the Walli Switches doesn’t work at all… 
New experimental Homey firmwares were released:
Changelog info:
Z-Wave
- Fixes various issues with (multi channel) associations on older devices.
I have a Homey Pro (2026), and the Walli switches configured in Double Mode are working again for me, including energy measurement.
BUT, Walli switches configured in Single Mode still doesn’t work at all…
A never ending story!
I’ve made a fix for Walli in Single Mode. Can you test version 3.8.16?
Test Environment:
Homey Pro (2026) with experimental firmware v13.4.1-rc.3
Fibaro Test Version App v3.8.16
Homey iOS Smartphone App v10.1.0.2074
Walli Switch connected with lamp
So this is a great improvement, and in my opinion, it’s working just like it did before the Homey firmware v13.4.0 and Fibaro app v3.8.10 updates. Thank you very much, @TeunVR! 
Good to hear it is working again.
But i do not really understand why the quick action in single mode does not work. In the web-app it was working this morning.
And what exactly is the issue with the status indicator? Can you post a screenshot?
I can confirm that the Quick Action Button (Single Switch Mode) works in the web app, but unfortunately not in the smartphone app.
Here is a screenshot taken from my iPhone:
The status indicator always shows that the light is on, even though the output is not turned on (red rectangles).
The ceiling lamp in the upper right corner, labeled “Deckenlampe HWR,” is actually turned on, as you can see from the brighter device tile. However, the Quick Action Button should also be displayed in blue to indicate that it’s turned on; unfortunately, that’s not the case.
ah yes, i had “Other” connected, not a light. Will look into it.
Did a quick test of Fibaro Test Release 3.8.16 with Smartphone App
Walli Switch in dual and single mode toggles correct.
And as I am using the Plugged in value assigned to “Other” I do have the power meter seen working. And the Quick Action is working with the Tile changing its colour.
When assigned the light the Quick Action ist mit working an the status light does not follow the switch status when toggled.
But toggle in device is working.
Did not tested web app now.
In the Mobile App the Quick Action only works with plugged in “Other”
It seems in the web app this behaviour is vice versa!
The error “missing capability listener for onoff.output2” occurred after the Homey Fibaro app update, exists in the latest stable, but is fixed in the latest text version for me.
