Try plugging the external storage drive to a USB 2.0 socket, it may tehn appear in safely remove hardware. If it does, I suspect there is something wrong with the USB 3.0 driver.
Despite running multiple tests on all system hardware with no failures the problem was a faulty RAM stick. This is why you should probably never trust one single test as a conclusive troubleshot. If I had just replaced/tested the sticks weeks ago this problem would have been fixed. Thanks for the help and apologies for the stupid/easy solution to this issue. The RAM did pass multiple tests of MEMtest and I let that be the deciding factor for croosing out RAM as the problem.