"Volume Control Slider" not changing sound using v1.9.5

Video and Audio transcoding/playing = works! I just can't adjust volume using the gnomecast slider control.

$ ffprobe -i Downloads/Joel\ Edgerton\ to\ Return\ as\ Owen\ Lars\ in\ Obi-Wan\ Series\ -\ Jedi\ Council-pCU2GE07KW4.mkv 
ffprobe version 4.1.4 Copyright (c) 2007-2019 the FFmpeg developers
  built with gcc 9 (GCC)
  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld ' --extra-cflags=' ' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libcdio --enable-libdrm --enable-libjack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmp3lame --enable-nvenc --enable-openal --enable-opencl --enable-opengl --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzvbi --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-libmfx --enable-runtime-cpudetect
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, matroska,webm, from 'Downloads/Joel Edgerton to Return as Owen Lars in Obi-Wan Series - Jedi Council-pCU2GE07KW4.mkv':
  Metadata:
    COMPATIBLE_BRANDS: iso6avc1mp41
    MAJOR_BRAND     : dash
    MINOR_VERSION   : 0
    ENCODER         : Lavf58.20.100
  Duration: 00:41:45.28, start: -0.007000, bitrate: 1303 kb/s
    Stream #0:0: Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
    Metadata:
      HANDLER_NAME    : ISO Media file produced by Google Inc.
      DURATION        : 00:41:45.269000000
    Stream #0:1(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
    Metadata:
      DURATION        : 00:41:45.281000000

File: Joel Edgerton to Return as Owen Lars in Obi-Wan Series - Jedi Council-pCU2GE07KW4.mkv Video: Video #1 (h264) Audio: eng (opus/stereo) Subtitles: Device: Chromecast (Unknown manufacturer) Chromecast: v1.9.5

FileMetadata(fn:/home/chris/Downloads/Joel Edgerton to Return as Owen Lars in Obi-Wan Series - Jedi Council-pCU2GE07KW4.mkv, ready:True, thumbnail_fn:/tmp/gnomecast_thumbnail_vzqlewvj.jpg, container:mkv, video_streams:[StreamMetadata(index:0:0, codec:h264, title:Video #1)], audio_streams:[AudioMetadata(index:0:1, codec:opus, title:eng, channels:2)], subtitles:[])


Stream #0:0: Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
Stream #0:1(eng): Audio: opus, 48000 Hz, stereo, fltp (default)```

keredson / gnomecast

"Volume Control Slider" not changing sound using v1.9.5 #100