I suspect an issue with "Sticky Folders", especially if you are new to version 6.x. Your Selection Criteria is very likely correct but you will need to reconfigure the server behavior to enable Dynamic Folder Reassignment since it is Static by default. I don't recall exactly where this setting is or what it is called as we are moving away from Avalanche, but I believe it is in something like the Mobile Device Server profile and it is a check box.
Hopefully you're not using Android devices with Avalanche because then you're toast:
Here is more detail on the dynamic folders:
Yep, it was that. Thank you very much Matt!!!