I recently upgraded to Kubuntu 18.04 from 17.10. After Wakeup from Suspend my paired Bluetooth device (Headphone) do not connect with the system. This was working fine in 17.10. After reboot it connects fine. Temporary fix, Restarting the Bluetooth service after each wakeup fixes this issue, sudo service bluetooth restart Or I need to remove the paired device and re pair it each time.
This is an issue in BlueZ, please report this bug against BlueZ.
Thanks David. Looks like fix will be released soon. https://bugs.launchpad.net/ubuntu/+source/bluez/+bug/1759628