Recently upgraded my old S10 to a new S20 and purchased a MicroSD card to hold all or most of my music files to play in the car when the radio reception fades away. I was very surprised to find that Samsung Music does not like playing M4A files, even though it should and did so on the S10. (Not a JRiver MC issue, but background). So I decided to convert all my M4A music files to FLAC. 4 days later, I had a new music library. All I had to do was copy the new FLAC files to my S20. Not so fast. I created a smart playlist to hold the files I wanted, then selected "send to" and select the S20 SD card. So far so good. After about 15-20mins the transfer stops and the action window says "Complete". But it is not. To restart the transfer I have to terminate MC28, restart it and restart the synch procedure. 15mins later ........ It stops again. So my question is: Why does MC28 (latest version on WIN10 latest SP) keep failing when transferring music files to an Android phone using a blistering fast SD card? Any suggestions ?