Vendor support suggested upgrading the firmware (I was on the latest firmware) so I followed their instruction - which nuked the keyboard's ability to use Bluetooth at all. No refund or replacement offered by vendor after reporting this.
I still use the non-broken one, exclusively in wired mode, and EVERY single time I use it, I have to perform the factory reset (Fn + z + j) in order to get the lights to work. Otherwise, cycling through the presets simply dims them until they're not visible.
I'm yet to find anybody with the same problems as me.