Poco::Glob does not work with UNC paths. The reason is that at one point collect() creates a DirectoryIterator for just the server name ("\srv\") which fails with an exception, causing the glob to bail out.
Was this fixed? From trunk code:
// In case of UNC paths we must not pop the topmost directory
// (which must not contain wildcards), otherwise collect() will fail
// as one cannot create a DirectoryIterator with only a node name ("\srv\").
int minDepth = base.getNode().empty() ? 0 : 1;