Sorry to hear this happening to you. My favorite LightRoomist and dive buddy had this happen to her sometime during the past year. As always I get called in to try to work it out.
Interesting thing is, it went away seemingly as mysteriously as it appeared, somewhat about the same time as she switched to the "cloud" version of the software.
In the meantime I updated everything I could, including "winders 7", her motherboard, and all hardware drivers including video drivers, USB drivers etc etc.
The symptoms were very similar to yours - random RAW files would suddenly develop a partial rainbow kind of banner and LightRoom would be allergic to them. Most often, re-copying the same file from a backup or the original card would rectify the problem until the next one went. Most subsequent times it would attack a different file; rarely the same one.
Adding RAM up to 16GB didn't stop the problem. Updating everything was a "maybe, maybe not" fix.
Of course, all the Abobe "pros" said it was IMpossible for LightRoom to corrupt an original RAW file as LightRoom never wrote to the file, to which I (as a former programmer in a long-ago lifetime) call BS! The act of opening a file to read it and then closing it improperly or forgetting to close it can easily cause corruption.
We tried all the things you mentioned above concerning card readers, external drives, cables and USB2 vs USB3, hubs vs motherboard direct port ad nauseum and none of those seemed to cure anything.
Since going to the "cloud" version, no more corruption is noted. Interesting coincidence, don't you think?
Sorry I can't actually be helpful!
PS: If you Google this problem you'll find incidents like this going back several years - on all kinds of hardware and operating systems - the common denominator is (you guessed it) LightRoom...