It looks like it in case of Music Library constructs the file string from wrong path parts.
In case of video it is OK. It takes the local mount path (/media/network/WHSvideos)
Code
09:39:55.0032650 >>> I <<< PlexLibrary::checkFileLocation -> Checking for local file
09:39:55.0033557 >>> D <<< PlexLibrary::checkFileLocation -> untouched remotePathPart: \\whs.home.local\Videos\
09:39:55.0034499 >>> D <<< PlexLibrary::checkFileLocation -> remotePathPart: \\whs.home.local\Videos\
09:39:55.0035553 >>> D <<< PlexLibrary::checkFileLocation -> localPathPart: /media/network/WHSvideos/
09:39:55.0036848 >>> I <<< PlexLibrary::checkFileLocation -> altered file string: /media/network/WHSvideos/@HD/WallE/hd1080-walle DTS-DD CZ PEPETOY.mkv
09:39:55.0745015 >>> I <<< PlexLibrary::checkFileLocation -> Local file found, will use this
but in case of music it uses the remote path part ( /whs.home.local/music)
Edit: I pasted the wrong lines before
Code
09:40:41.0103317 >>> I <<< PlexLibrary::checkFileLocation -> Checking for local file
09:40:41.0104172 >>> D <<< PlexLibrary::checkFileLocation -> untouched remotePathPart: \\whs.home.local\Music\
09:40:41.0105081 >>> D <<< PlexLibrary::checkFileLocation -> remotePathPart: \\whs.home.local\Music\
09:40:41.0105912 >>> D <<< PlexLibrary::checkFileLocation -> localPathPart: /media/network/WHSmusic/
09:40:41.0106946 >>> I <<< PlexLibrary::checkFileLocation -> altered file string: /whs.home.local/music/Avril Lavigne - Avril Lavigne (2013)/01. Rock n Roll.mp3