1. SD-Card failure
I had several SD cards, who could be used for a while, but after writing 30 or 50 or 75%, they ceased being writable.
MMA was in the sync process, I just observed, that suddenly the download in percent per title did not increase anymore, it stayed at 0% - then the next title... and so on.
MMA tried to finish the sync process, and at the end, only the message: xxx files downloaded, yyy files download failed. Of course, no playlists were transferred/created.
I tried to sync again, no other error message than download failed for all files.
Only then, when I observed the messages from the system, I realized that the SD card was suddenly "read only".
EXPECTED: MMA should realize that the medium is not writable anymore and raise a helpful error message.
(Took me several days to find out, that all cards that I bought had this strange issue.)
2. Replace broken SD card
I had all my files on a SD card. When I exchanged the SD card (of course all files missing) and started the sync process, it transferred all (now) missing files again to the new SD card: fine. But all playlists (which were greyed out after replacing the card) remained greyed out after successfully (re-) download all files to the new SD card.
EXPECTED: MMA should transfer all files AND update the playlists after downloading all files.
3. Playlists update I...???
Then (to get the playlists "right" again) I removed ALL playlists from the sync list and started the transfer. Usually, I expected that MMA would delete all files and playlists. It deleted quite a bunch of files, but after finishing without errors about >50GB of music data remained on the sd card (before it was ~75GB)? How that? I only synced playlists, nothing else.
EXPECTED: When I exclude the playlists from the sync list AND enable "deleting all unselected files" - ALL files should be removed during sync - nothing left on the device!!!
Secondly, ALL playlists remained (greyed out) on the phone (in MMA).
EXPECTED: When I exclude a playlist from sync, it has to be REMOVED from the device, no trace left.
It seems, if a playlist is once on the device, it remains there forever.
4. Playlists update II ...???
Then I enabled all my playlists again (in the sync list), MMA downloaded again all files (probably)... but the playlists remained greyed out as before.
EXPECTED: When I sync a playlist successfully, it should also be updated that it is displayed like after the first successful transfer/sync.
5. Multiple device accounts on the server
After all this strange and time consuming trials (just to sync my music to a standard Samsung phone), on my PC I have now 5 devices all with the same name... not knowing which is currently used and which I can remove.
EXPECTED: One phone (storage) - one account... no matter what happens else.
6. Removing a device account, it is not recognized anymore
Now I removed all devices from the server, in hope, that it would appear ONE new account on reconnect, but nothing happened anymore. The device was not recognized anymore by the server. No sync possible.
EXPECTED: After removing an account and reconnecting the device, it should appear as a new, unknow device, like the first time.
Finally, I had to remove all (which were a lot) entries in the json file connected with this REMOVED account. After this, it did reconnect again, but now it already has again 5 different accounts, all with the same name for one phone.
It all looks like quite strange bugs in the sync behavior - good luck for (hopefully) fixing and improving MMA
