Yes!
When I start Music via bubbleUPnP on my PI, it´s still good to control Volume/Play/Pause and next Track over the GPIO buttons (which trigger Volumio as does the GUI, sorry for mixing GPIO and app). So I don´t have to turn on my Smartphone all the time. Thought this should work, especially as next and previous Track buttons work. Just Play/Pause does not.
Just found, that this issue was already posted in the past:
https://community.volumio.com/t/volumio-in-rpi-as-upnp-renderer-don-t-pause-play-bubbleupnp/11811