I have been getting this with one on my ML2 a lot lately:
[2019-01-06 09:09:30] FutureBit Write error: Input/output error
It will work after being re-plugged in but only for a day or so.
Anyone have any clues as to what is causing this?
That means device dropped out completely from hub/USB port, and it will not reconnect on it's own, you need to unplug it to have it back.
I would try different USB hub / different USB cable.