I'm having a similar problem that I find in the forum that happen before but with the MC17 version. The problem occurs playing to my denon receiver 3312 with the MC20 . I click on denon on the playing now, then MC starts becoming laggy. I then try to play a song then it will freeze for a moment then have a message pop up saying "there was a problem controlling the selected DLNA device. Double-check your device, server and network settings.
Sometimes it works for a while, if first I was listening to internet radio.
Sometimes it also power on the denon but always have problem to control the device and can not play a song, it try to play 3 song and after that a message that can not play appears. "Something went wrong with playback"
I read in the forum that at that time the problem will be result with the 17.0.178 release of the MC17 but now I have the MC20.
I'll be very grateful if someone can help me figure out how to hear music again in the living room with my PC