Try creating a SP profile to the Pi. Edit the following file:
sudo nano /etc/systemd/system/dbus-org.bluez.service
Find the following line and add a compatibility flag '-C' to the end:
Additionally, add the following line after the above:
ExecStartPost=/usr/bin/sdptool add SP
Save and reboot. Try removing the device then repairing and trusting the device with bluetoothctl.
Then connect to the device with terminal via:
sudo rfcomm watch hci0
sudo rfcomm connect 0 <bluetooth address> 1
If that doesn't work you can also try adding pi to the lp group
sudo adduser pi lp
Recently I have created a Repo on GitHub that sets the Pi up as an Audio Receiver that allows for auto pairing of bluetooth devices, sets up airplay for iDevice users, and allows auxillary line input. The installation works great on the latest raspbian, it is best to use a fresh install. There are two versions, one that is a Home version that uses an existing wireless network for the AirPlay, the other is a Car version that creates its own Wireless Access Point without internet so that the iDevice can use AirPlay. It would be easy enough to add a hotspot for internet access as well.
In terms of this specific topic, the bluetooth works flawlessly and allows for users to control the bluetooth volume with their device.