Logitech G815 keyboard recognised but then not working

[DeathStar Darth]

Normally I run the UnRaid server through a KVM switch and have no problem with it recognising my Logitech G815 keyboard.

 

I've had reason to move my kit around and plugged the keyboard directly into the server (motherboard usb, not a usb hub hanging off it).

 

At boot time it (the keyboard) springs to life in all its multi-coloured splendour, and I can use it to select bootmode (gui, safe etc) and all proceeds as normal. Midway through the boot process, all the lights go off and the keyboard is no longer of any use.
I've had to pull out my old Mac keyboard to get around this for now

 

This is from the log during boot:

Aug  8 11:15:00 TheDeathStar kernel: hid-generic 0003:1B1C:1C07.0001: hiddev96,hidraw0: USB HID v1.11 Device [                                                ] on usb-0000:07:00.1-5/input0
Aug  8 11:15:00 TheDeathStar kernel: input: Logitech G815 RGB MECHANICAL GAMING KEYBOARD as /devices/pci0000:00/0000:00:01.2/0000:02:00.0/0000:03:08.0/0000:07:00.3/usb4/4-1/4-1:1.0/0003:046D:C33F.0002/i
nput/input1
Aug  8 11:15:00 TheDeathStar kernel: hid-generic 0003:046D:C33F.0002: input,hidraw1: USB HID v1.11 Keyboard [Logitech G815 RGB MECHANICAL GAMING KEYBOARD] on usb-0000:07:00.3-1/input0
Aug  8 11:15:00 TheDeathStar kernel: input: Logitech G815 RGB MECHANICAL GAMING KEYBOARD Keyboard as /devices/pci0000:00/0000:00:01.2/0000:02:00.0/0000:03:08.0/0000:07:00.3/usb4/4-1/4-1:1.1/0003:046D:C3
3F.0003/input/input2
Aug  8 11:15:00 TheDeathStar kernel: input: Logitech G815 RGB MECHANICAL GAMING KEYBOARD Mouse as /devices/pci0000:00/0000:00:01.2/0000:02:00.0/0000:03:08.0/0000:07:00.3/usb4/4-1/4-1:1.1/0003:046D:C33F.
0003/input/input3
Aug  8 11:15:00 TheDeathStar kernel: input: Logitech G815 RGB MECHANICAL GAMING KEYBOARD Consumer Control as /devices/pci0000:00/0000:00:01.2/0000:02:00.0/0000:03:08.0/0000:07:00.3/usb4/4-1/4-1:1.1/0003
:046D:C33F.0003/input/input4
Aug  8 11:15:00 TheDeathStar kernel: hid-generic 0003:046D:C33F.0003: input,hiddev97,hidraw2: USB HID v1.11 Keyboard [Logitech G815 RGB MECHANICAL GAMING KEYBOARD] on usb-0000:07:00.3-1/input1

 

Definitely not a show-stopper, but I was wondering if anyone might be able to suggest a way to get it working so I can keep just one keyboard around until I can revert to my former kvm setup.