Hi all,
this is my first post so i hope you will be kind with me 
This issue is still part of volumio 3 (volumio toggle not working for play command). Can anybody confirm whether the fix mentioned by ash is still working with this version or is there any other fix for this (i don’t want to break my system)? I was hoping that there will be a fix integrated by volumio directly because if you attach this solution to your system it gets removed after every system update.
For the future i am planning to use an irremote for controlling volumio and since am using spotify connect a lot this is an important issue for me (and maybe for others, too). 
volumio version: v3.173
spotify connect plugin: v3.0.7
raspberry pi 4
USB DAC