It is missing indeed, however, this solution was provided by someone else so I am afraid I won’t be of much help here as to tell WHY you don’t have have the resume filled in.
I did however looked for you online for how to set the resume and here they say to use the command: sudo update-initramfs -u… BUT I don’t know myself exactly what that command does to the system.
It couldn’t hurt to see and discover what that command does before using it 
I am a noob in learning Linux still, but I help where I can!