Sync deletes tracks in stead op copiing from MB to Android phone

[pdpourcq]

Hello,
I want to sync my tracks to my Android phone Samsung Galaxy S8). Until some time ago this worked fine. When synchronization starts I get synchronization failed. MB starts to erase the tracks on the device or gives copy failed - The specified data type is invalid ...
(Exception from HRESULT: 0x8007070C)
Instead of copying the new tracks, the existing ones are erased. very scary  >
All the tracks are available on a NAS and reachable by MB!

My settings are (screenshot)
http://www.mediafire.com/file/17xqn8okfoqbjsb/MB+sync.jpg/file

[Steven]

It is necessary for MB to delete the target file on the android device before copying the one from your NAS.
The error that occurs when copying: 0x8007070C = "May be used to indicate that an invalid data packet was received from the device."
I can't help any further as to why the error happens. You could try an android forum to see if anyone can shed light on what might be the problem