UPnP Not Working

[Alepsis]

VLC 2.1.5 Rincewind, Mac OS X 10.7.5

Problem: I have two UPnP servers on the LAN, Twonky and Asset UPnP. Both are fully accessible from iPhone, iPad, and network players, but VLC can't access either.

Symptom: Launch VLC, go to Local Network: Universal Plug'n'Play. One of the servers (never both) shows up in the playlist, with a yellow triangle. Click, choose 'Expand Node', nothing happens. Double click, nothing happens.

All firewalls are off, and VLC can play files from the servers via Samba.

Any suggestions?

Thanks.

[Alepsis]

Update:

(1) Trashed all VLC prefs -- made no difference.

(2) Other devices on the network (iOS players, incl VLC for iOS; hardware players) have no problem discovering the UPnP servers.

(3) On the same Mac, XBMC has no problems discovering the servers or playing media served by them.