This sounds like a drive that totally needs to be wiped and reformatted. If the manufacture could not find a problem with the drive (and ill assume they did a read/write test and diagnostic) then I would dump your files off of the drive and totally re-format it as a Mac drive . But if this does not work – if possible return the drive.
My problem in this thread was different and I had no “read” problems just a “write” permission problem.