To all those who are having problems synchronizing with MM for Windows using the USB cable... (MTP sync) to EXTERNAL SD card.
1. Make sure your card is recognized in Windows explorer first and that you can open and view the files.
2. Make sure that MMW can see your card (recognized as CARD and not PHONE which is the internal memory).
3. Make sure MMW reports the correct amount of memory.
4. Make sure and double check all your sync settings are correct.
5. If MMW is continuously scanning your card is not a problem - you can still sync.
6. If it is the first time you are syncing, make sure MMW has calculated correctly how many songs are going to be copied.
7. Make sure there is enough room on the card.
8. When a sync has completed, your synced tracks will show as a BLUE bar. Unrecognized data will show up as a YELLOW bar.
9. If you are syncing a second time (disconnect the phone and reconnect it), and if you do NOT see a BLUE bar equal to the number of tracks you already synced, YOU HAVE A PROBLEM. To verify this, below the bar, you can click on the first item and it will rotate from MBs, no. of tracks, etc, giving you more information on the recognized tracks that have been previously synced to the phone by MMW. If this number is not what you expect then you have a problem with your CARD!
10. under the card node, there are several nodes. One of them is called Music. When you click on this you will see all RECOGNIZED previously synced tracks.
11. You can try syncing again, but if MMW does not recognize many songs that have already been transfered, it will try to transfer them again... naturally. This is why it reports sometimes that there is not enough room on the card, because it is almost full and it must transfer all the songs again, thinking that they will take additional space! Bottom line... YOU HAVE A PROBLEM WITH THE CARD!!! MMW MTP sync is not working smoothly because of a fundamental hardware flaw!
If you are having some of these problems with your new shiny high capacity expensive card, LOL please... save your time.... Try first a smaller test on the internal memory. Get a feel of how things should be working. The internal memory is ALWAYS much faster and more reliable that external microsd cards. You will get a feel for what you should be looking for in a successful sync.
When you are confident, then try with another external card and see if it behaves differently (anything will do get an older smaller card from different company) - check the differences.
Do small test runs that take minutes and NOT hours to complete. Don't waste your time.
When you see a light of hope, in successful syncs, then you can try your problem card again. Try small syncs first. Always disconnect and reconnect the phone after successful sync to see if what went to the phone is recognized in the BLUE bar. If not then you are having problems with the card. If not, then continue until you have all tracks transfered but at least you are now sure of a consistent behaviour. If not then you are having problems with the card.
An external sd card does not have to be formatted in a different filesystem to work. exFAT is usually the file system of choice for a reason. the manufacturer has chosen this fs for a reason. It should be perfect. (In my case I formatted to FAT32 and saw stability in my transfers (Sandisk Ultra 64Gb MicroSDXC I) but my transfer speed over USB went to the garbage at around 3MB/s. This is NOT a solution!) If it does not work with exFAT you have a problem with the CARD!!!
Now, if from what you have read above, you think that maybe there is a problem with your card, and you do not want to believe it because you will have to go through all the trouble of RMA etc, please try to get it through your head. Do not be stubborn like me wasting 3 years trying to get it to work properly. It wil not. If it is failing, you have a problem with the card.
Some final checks would be to check if you have the latest phone upgrade and also check if your phone supports the particualr card (e.g. Note 3 and Note 4 have completely different card support. Note 4 supports much faster transfer rates from the same cards).
So if you have eliminated most other things, then all you are left with is a problem with the card.
Check with the manufacturer. Many companies e.g. Sandisk have huge warranties on their cards. You can easily initiate a RMA request and get a reply and resolution on the same day. After 3 years, this is what I did and sandisk has been more than accommodating.
So bottom line, if you have done all you can and it still does not work, RMA your card and insist on getting some other model - explain this in your RMA request.
PS. I do not cover fake cards above. When you get a new card check it first if it is fake before you start the above tests. There are software available to check this for you e.g. h2testw https://www.raymond.cc/blog/test-and-de ... h-h2testw/