UPDATE - It appears it might be the device - as I just installed EDIT on windows and get the same issue.
SOLVED!!!
So Google came up with someone who had a missing tone and that was stopping the sync. So after I went through all my tones 1 at a time, I found 5D was all gibberish.
Saved over it with a fresh tone - and Bingo!! Problem solved!
Don't know it got corrupted in the first place, but it's working now - WINNER!