I installed JRMC32 today, and it copied all the settings from my working copy of JRMC31, including all the settings for Media Network.
I pulled out my tablet which has BubbleUPNP installed. My PC did not appear as a DLNA media server or a renderer. I tried the same with mConnect with the same result.
I unchecked and rechecked the Media Network tick box in both "Audio-Advanced Features" and "Media Network" and restarted JRiver. Same result. I rebooted the PC - same result.
I then exited JRMC32 and launched JRMC31. DLNA started working again. My PC now appears as a library and a renderer with JRMC31, but not JRMC32, using the same settings.
I am not sure if the software is broken, or I have missed a setting.