OpenMarine

Though the GPS is clearly displayed by lsusb (U-Blox AG[u-blox 8]), the only device found in SERIAL 3.1.3 is the USB 3.0 Host Controller !
Rebootting, removing and re-installing SERIAL : no success ?  until now it worked perfectly !

Is the USB 3.0 Host Controller a Hub?

Have you tried connecting the GPS directly?

Have you considered power or wiring issues?