Your batch status may be "In progress" at 99%. It's the expected behavior.
Soundiiz is doing a matching process before adding elements to the destination service. That means we have matched (or not) all your items in your batch and Soundiiz is now in the "addition" process.
So, don't worry; you will receive an email once the process ends. It could take a few minutes, like some hours, as it depends of the destination service and the volume to be transferred.