Web player transport controls stuck on 'spinning arrows' rather than play/pause.

Try to click 'play' and 'play next' button next to track listings, get no response.
Try to click 'play last' button next to track listings, 'Song will be played last' alert pops up, queue remains empty.
Troubleshooting Steps:
1. Tried accessing server from Android app on phone. No issues, can stream music as normal.
2. Tried switching browsers between Chrome 50.0.2661.94, Firefox 46.0.1, Internet Explorer 11.0.9600.18282 (all on Win 7 x64). No difference, same results as above.
3. Tried clearing browser cache on all browsers from item #2. No difference, same results as above.
4. Tried music playback with another HTML5 player (http://terrillthompson.com/tests/html5-audio.html). Produces sound.
5. Tried music playback on Demo Subsonic server (http://demo.subsonic.org). 'Play/Pause' and per-track 'Play', 'Play Next', 'Play Last' buttons work as expected.
Playback Application and version:
Default HTML5 web interface
Subsonic Version: 6.0 (build a7857c) – April 30, 2016
Server Version: jetty-6.1.x, java 1.7.0_76, FreeBSD (60.7 MB / 148.5 MB) (FreeNAS-9.10-STABLE-201605021851)
Hardware Platform:
* ASRock AM1-H mini-itx motherboard
* AMD 5350 (quad core 2.05GHz)
* 8GB DDR3-1333
* 16GB SanDisk Ultra Fit USB drive (boot)
* 4 x 3TB WD Green HDD (storage, ZFS RAIDZ1)
Java Memory Limit: 150MB
Output from ffmpeg -i:
- Code: Select all
ffmpeg version 2.8.4 Copyright (c) 2000-2015 the FFmpeg developers
built with gcc 4.2.1 (GCC) 20070831 patched [FreeBSD]
configuration: --prefix=/usr/pbi/subsonic-amd64 --mandir=/usr/pbi/subsonic-amd64/man --datadir=/usr/pbi/subsonic-amd64/share/ffmpeg --pkgconfigdir=/usr/pbi/subsonic-amd64/libdata/pkgconfig --enable-shared --enable-gpl --enable-postproc --enable-avfilter --enable-avresample --enable-pthreads --disable-libstagefright-h264 --disable-libutvideo --disable-libsoxr --cc=cc --extra-cflags=' -I/usr/pbi/subsonic-amd64/include' --extra-ldflags='-L/usr/pbi/subsonic-amd64/lib ' --extra-libs=-lpthread --enable-memalign-hack --enable-libaacplus --disable-indev=alsa --disable-outdev=alsa --disable-libopencore-amrnb --disable-libopencore-amrwb --disable-libass --disable-libbs2b --disable-libcaca --disable-libcdio --disable-libcelt --disable-libdc1394 --disable-debug --disable-htmlpages --disable-libfaac --disable-libfdk-aac --disable-ffserver --disable-libflite --enable-fontconfig --enable-libfreetype --disable-frei0r --disable-libfribidi --disable-libgme --disable-libgsm --enable-iconv --disable-libilbc --disable-indev=jack --disable-ladspa --enable-libmp3lame --disable-libbluray --enable-mmx --disable-libmodplug --disable-openal --disable-indev=openal --disable-opencl --disable-libopencv --disable-opengl --disable-libopenh264 --disable-libopenjpeg --disable-libopus --disable-libpulse --disable-indev=pulse --disable-outdev=pulse --disable-libquvi --enable-runtime-cpudetect --disable-librtmp --enable-libschroedinger --disable-ffplay --disable-outdev=sdl --disable-libsmbclient --disable-libsnappy --disable-libspeex --enable-sse --disable-libssh --enable-libtheora --disable-libtwolame --disable-libv4l2 --disable-indev=v4l2 --disable-outdev=v4l2 --disable-vaapi --disable-vdpau --disable-libvidstab --enable-libvorbis --disable-libvo-aacenc --disable-libvo-amrwbenc --enable-libvpx --disable-libwavpack --disable-libwebp --disable-x11grab --enable-libx264 --enable-libx265 --disable-libxcb --enable-libxvid --disable-outdev=xv --disable-libzmq --disable-libzvbi --enable-gnutls --disable-openssl --disable-version3 --enable-nonfree
libavutil 54. 31.100 / 54. 31.100
libavcodec 56. 60.100 / 56. 60.100
libavformat 56. 40.101 / 56. 40.101
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 40.101 / 5. 40.101
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.101 / 1. 2.101
libpostproc 53. 3.100 / 53. 3.100
Missing argument for option 'i'.
Error splitting the argument list: Invalid argument
Last umpteen log file lines:
- Code: Select all
[5/6/16 3:00:14 AM PDT] INFO MediaScannerService Scanned media library with 9253 entries.
[5/6/16 3:00:14 AM PDT] INFO MediaScannerService Marking non-present files.
[5/6/16 3:00:14 AM PDT] INFO MediaScannerService Marking non-present artists.
[5/6/16 3:00:14 AM PDT] INFO MediaScannerService Marking non-present albums.
[5/6/16 3:00:14 AM PDT] INFO MediaScannerService Completed media library scan.
[5/6/16 3:00:15 AM PDT] INFO PlaylistService Starting playlist import.
[5/6/16 3:00:15 AM PDT] INFO PlaylistService Completed playlist import.
[5/6/16 7:19:01 AM PDT] INFO TranscodeInputStream Starting transcoder: /var/db/subsonic/transcode/ffmpeg -i /media/albums/swedish electro scene - 'swedish electro vol 3'/[SwedishElectroVol3][42]Sidewalk Cindy - Lose Myself In You (Candide Remix).flac -map 0:0 -b:a 128k -v 0 -f mp3 -
[5/6/16 7:24:11 AM PDT] INFO TranscodeInputStream Starting transcoder: /var/db/subsonic/transcode/ffmpeg -i /media/albums/swedish electro scene - 'swedish electro vol 3'/[SwedishElectroVol3][43]Made In Heaven - The Last Of The Loving Feeling (Original 1988 Demo).flac -map 0:0 -b:a 128k -v 0 -f mp3 -
[5/6/16 7:27:27 AM PDT] INFO TranscodeInputStream Starting transcoder: /var/db/subsonic/transcode/ffmpeg -i /media/albums/swedish electro scene - 'swedish electro vol 3'/[SwedishElectroVol3][44]Candide - Odets Serenad (Full Length Version).flac -map 0:0 -b:a 128k -v 0 -f mp3 -
[5/6/16 11:31:41 AM PDT] WARN SettingsService Failed to validate license.
[5/6/16 6:19:38 PM PDT] INFO TranscodeInputStream Starting transcoder: /var/db/subsonic/transcode/ffmpeg -i /media/albums/swedish electro scene - 'swedish electro vol 3'/[SwedishElectroVol3][50]Social Ambitions - Robot (2015 SEC Edition).flac -map 0:0 -b:a 128k -v 0 -f mp3 -
[5/6/16 6:19:40 PM PDT] WARN RESTFilter Error in REST API: EofException
[5/6/16 6:19:40 PM PDT] ERROR JAXBWriter Failed to marshal JAXB
[5/6/16 6:19:40 PM PDT] ERROR RESTFilter Failed to write error response.
[5/6/16 6:19:41 PM PDT] INFO TranscodeInputStream Starting transcoder: /var/db/subsonic/transcode/ffmpeg -i /media/albums/swedish electro scene - 'swedish electro vol 3'/[SwedishElectroVol3][50]Social Ambitions - Robot (2015 SEC Edition).flac -map 0:0 -b:a 128k -v 0 -f mp3 -
[5/6/16 6:26:31 PM PDT] WARN CoverArtController Failed to create thumbnail for [REDACTED - 17 similar]