adb backup command on non-rooted device creates an empty backup file?

I recently tried to backup my Motorola Moto G2 XT1068 phone running Lollipop 5.0.1 and after connecting it over USB with usb-debugging ON and I ran the adb backup command to backup my device completely and this question Full backup of non-rooted devices and the solution guided me. However running the following adb command, adb backup -apk -shared -all -system -f D:/backup.ab din't work in my case. The command instructed me to Unlock my device and confirm the backup operation. However doing so displayed the Backup started and Backup completed toast message back to back in just one second duration. And obviously the backup.ab file generated too was an empty 0kb file. Removing and changing the parameter din't help either.