G Drive 4TB USB (with important data) not showing up on iMac


I was wondering if someone could help me as I seem to be a bit confused.

I have a G DRIVE USB 4TB - which I have kept safe & secure on my travels filming. I have tried to connect it to my iMac but it does not recognise it - I have checked Disk Utlity and it does not show there. There is no signs of damage, the ports look fine and I have even bought a replacement USB 3.0 cable to try, and unfortunately, still no luck.

The power works as the “G” lights up a white light once plugged in - it just seems that my computer is not detecting it.

Has anyone got any solutions as there is some footage on there I need to retrieve?