Yes, same problem here. Been thinking about canceling my account and moving back to concentrating on my record collection and this is the last bit. Bye Stupidify, you clearly don't care enough of your customers to pay attention to a simple yet a big and very common problem such as this.
Re: Controlling volume over spotify connect macbook pro
I have the same issue while working on my Macbook Pro (2015 - OSX 10.11.6) in my kitchen with wireless speakers connected to my sender in the living room playing from my iphone SE volume control is greyed out. Sometimes you just need to quickly push on the volume to match your workflow;) So pretty please make it possible or say why its not working. Then I can at least think about changing one link in this bad chain.