I'm having issues with the MagicFill syncing as well. For now, I suggest that you do what I've been doing:
Go to your Windows Explorer/My Computer, click the address bar and type in %appdata% and hit Enter, then go into Maxthon3 folder, and Users and go into your account folder. Then copy the file in the MagicFill folder on a USB, or email it to yourself as the file is very small. Then save it in the same location on your 2nd machine.
Sorry, I know this isn't the answer you're looking for, but hopefully someone else has a solution.