Child devices are broken in the new Alexa skill. 
Being discussed in the big thread:
New SmartThings Alexa skill (2020)
My understanding is that support for child devices is also going away in the new V3 app, which is why there are so many posts about fibaro double switches not working, So I’m not sure if they are planning on fixing that for Alexa or not.
That would mean the DTH for the Qubino would have to be Rewritten to not use child devices.