Confirming same issues on my end. Just upgraded via fresh install a couple days ago from Win 7 to Win 8.1 x64. Running VLC 2.1.0 32-bit. Nothing shows with UPNP selected under Network and shows no machines with shared media. If I click elsewhere, such as Network Streams, then click back on UPNP, Windows informs me VLC 2.1.0 has stopped working and gives me the option to close the program. All files I am wanting to access are on a Nix box, and it is running MiniDLNA. I just shared the folders within Nix and I can access them OK from File Explorer via the Network in Windows. This is an OK temp fix, but would really like to use VLC for this
Everything else with VLC seems to work just fine. I thought I had remembered Windows popping up in the past the first time UPNP is used in VLC, and asking to allow features though Windows Firewall? Did not happen this go around, but I checked firewall settings and VLC is OK on private network. Hope the dev team can figure this one out, will be poking around as well.