First, on 4 discs purchased, I met the same problem with 2 hard drives: they behave in exactly the same way. Each disk has two phase 1 to the first connection after long inactivity (qqes h) and after deco / reco. If you format the drive in one phase, the partitions will not be recognized in the other phase (unpartitioned). This is a very strange phenomenon that I can not explain but very real and found on 2 of 4 discs. I contacted the seller to find out if there was a solution, I await the answer. The only way I've found for now is to format the disk in Phase deco / reco and to use it, I connect / disconnect / reconnect. It's still pretty tedious for a new hard drive ...
Second, sometimes the disk starts to make noise (a very audible GRR like the old disks). The noise never happens during the writing is rather silent and lasts long (qqes tens of minutes). If that happens, deco / reco (it is finally the solution to all his problems).
The prints are fast USB 2.0 not tested 3.0.