the clip sport plus only support Audible enhanced format .aax. see the link below. Also there is a board for the clip sport plus so this post may be moved to the correct board.
https://kb.sandisk.com/app/answers/detail/a_id/14130/
SanDisk Clip Sport Plus/Sport/Jam/Voice supported audio/music formats
AA / AAX (audible) (Clip Sport Plus/Voice Audible Enhanced Audio .aax) (Clip Sport/Jam Format 4 and Audible Enhanced Audio .aax)
AAC / M4A (Files up to 15 mins in length)
FLAC (16 bit)
MP3
Ogg Vorbis
WAV
WMA (DRM free)
NOTE: Clip Sport Plus/Sport/Jam/Voice supports audiobooks obtained from Audible and DRM free Audiobooks only.
