Yeah, that agent is supported.
Have some time now, so will be looking at this issue now.
Here's the log file.
I tried to do all the actions that seem to cause the problem (editing the xml file, saving through the web interface, syncing, etc.) during this log.
The log file shows this:
Exception loading user preferences from /var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Plug-in Support/Preferences/com.plexapp.plugins.trakttv.xml (most recent call last):
File "/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Plug-ins/Framework.bundle/Contents/Resources/Versions/2/Python/Framework/code/preferences.py", line 168, in _load_user_file
prefs_xml = self._core.data.xml.from_string(prefs_xml_str)
File "/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Plug-ins/Framework.bundle/Contents/Resources/Versions/2/Python/Framework/components/data.py", line 161, in from_string
File "lxml.etree.pyx", line 2743, in lxml.etree.fromstring (src/lxml/lxml.etree.c:52665)
File "parser.pxi", line 1573, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:79932)
File "parser.pxi", line 1452, in lxml.etree._parseDoc (src/lxml/lxml.etree.c:78774)
File "parser.pxi", line 960, in lxml.etree._BaseParser._parseDoc (src/lxml/lxml.etree.c:75389)
File "parser.pxi", line 564, in lxml.etree._ParserContext._handleParseResultDoc (src/lxml/lxml.etree.c:71739)
File "parser.pxi", line 645, in lxml.etree._handleParseResult (src/lxml/lxml.etree.c:72614)
File "parser.pxi", line 585, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:71955)
XMLSyntaxError: Opening and ending tag mismatch: password line 13 and PluginPreferences, line 16, column 21
Looks like the preferences file isn't valid so the plugin is failing to receive any username and password.