This is an excerpt from a firmware update posting I'm about to drop that you may or may not find useful...
"To be VERY clear, even when I was able to update the firmware, when reconnected to my target system, with four USB 3.0 slots, the Faderport 8 only functioned intermittently, as though the USB connection was being continually broken and/or reset. So, as was also described (sorta) in this community, I discovered that if I inserted an ancient, off-brand, non-powered USB hub (assumed to be USB 2.0 as it was designed for use with Windows 2000 (!). I had forgotten that I still had this thing and had never once used it), when I inserted this legacy hardware into the connection chain between the desktop and the Faderport 8, (e.g. Faderport 8 to ancient USB hub, to USB 3.0 slot on desktop) my Faderport 8 worked perfectly; just as advertised. Total guess here, but it seems my USB 3.0's are not "falling back" to USB 2.0 as they should. Again, a guess.
"To save those few poor saps out there like me (and perhaps some annoyance to Presonus tech support), Presonus might add a "catch line" of code to the UC app that lays out quite plainly for the user in a text file or whatever, when a USB mis-match occurs. Just having the newly unboxed unit flashing and crying foul when there is a simple mis-match is totally disheartening. Some less tenacious folk might just bail on the product-line rather than work it out for themselves. Better yet, Presonus might seek to catch this issue in software and run a sub-routine as a software workaround. My take, of course."
All the best!'