🚀 go-pugleaf

Sounds familiar.  Being left-handed, it was natural for me to put the
external drive on the left set of the Mac -and that's the way I first
set the machine up.  Within the first week I started having trouble
copying files to the external drive, and things quickly deteriorated
to the point where it claimed that every disk I inserted was unreadable.
Took the drive in to my trusty dealer ...who could of course find 
nothing wrong with it.  Hooked it back up and everything worked fine
[you can imagine how sane I felt at that point].  That is, everything
worked fine for a couple of weeks.  Then the same deteriorata.  So I
started fiddling everything I could think of, and finally hit on the
right-side-of-the-machine solution.  And it's been all sweetness and
light since then.

p.s.  Things also work perfectly well with the cable going straight out
from the back of the Mac and the front of the drive facing away from
the machine.  But this isn't the handiest arrangement.