Same problem …. bought two 2TB external hard drives from China ….. one seemed to work when I copied data to it. But would not take the 8.57gb I was sending [ MS-DOS [FAT] ] has a limit of 4gb. Then my MAC would simply not recognise the external drive. I tried all the recommended fixes in Disc Utility on both my rather large Macs [in my recording studio]. One is brand new iMac.
Neither of the two discs are seen by either Mac … I shall turn the problem over to my ‘man’ on Monday [now Saturday] … but, as with most folk, I won’t give in … wasting hours on this problem. Can’t find the answer!