USB connected external hard drive which powers up, lights up, and makes noise like hard drive spinning but none of the three computers to which it was connected would show the connection existed.
In normal ops, a window opens asking what you want to do with the external.
Failing that, clicking 'computer' will bring up icons of the various drives and one clicks on the 'external' often characterised as F.
There are no apparent problems with the usb cord(s) used in this situation.