File format not supported when the file is on SD card

SanDisk MP3 players SanDisk® Clip Sport
4

Maybe take a look at this discussion from Jan 2015 on this SanDisk Forum.

http://forums.sandisk.com/t5/SanDisk-Clip-Sport/Micro-SD-Card-Size-with-FLAC-FIles/td-p/336666