The bitrate is in the caps, though:

gst-discoverer-1.0 -v ~/Source/gupnp-dlna/tests/media/strict/audio/NiN_Ghosts_I_1_BASE.wma
Analyzing file:///home/jens/Source/gupnp-dlna/tests/media/strict/audio/NiN_Ghosts_I_1_BASE.wma
Done discovering file:///home/jens/Source/gupnp-dlna/tests/media/strict/audio/NiN_Ghosts_I_1_BASE.wma

Topology:
  container: video/x-ms-asf
    audio: audio/x-wma, wmaversion=(int)2, bitrate=(int)64000, depth=(int)16, rate=(int)44100, channels=(int)2, block_align=(int)2973, codec_data=(buffer)008800000f0000000000
      Codec:
        audio/x-wma, wmaversion=(int)2, bitrate=(int)64000, depth=(int)16, rate=(int)44100, channels=(int)2, block_align=(int)2973, codec_data=(buffer)008800000f0000000000
      Additional info:
        None
      Language: de
      Channels: 2
      Sample rate: 44100
      Depth: 16
      Bitrate: 0
      Max bitrate: 0
      Tags:
        taglist, container-format=(string)ASF, audio-codec=(string)"WMA\ Version\ 8", language-code=(string)de;
      

Properties:
  Duration: 0:00:30.243000000
  Seekable: yes
  Tags: 
      container format: ASF
      audio codec: WMA Version 8
      language code: de

Sample file is at https://git.gnome.org/browse/gupnp-dlna-media/tree/strict/audio/NiN_Ghosts_I_1_BASE.wma