Is it possible to select multiple contact folders for sync and / or how are sub folders treated?
You can create multiple profiles, each profile accessing one subfolder. But then you have to change the profile, if you want to sync each folder. Currently there is no automatic update for multiple profiles implemented, but we are planning it. For now, some manual action (changing the profile and press sync button) is required from your side. Keep heads up for this feature implemented
I've moved all contacts to the default folder and separated by category. I'll monitor for an update that includes multiple folder functionality.