Initially after plugging the keyboard into my pc via USB, iCue stated there was a firmware update. My firmware was 5.11.xx. The update was for 5.13.xx. After following the instructions iCue gave, the update seemed unsuccessful because my keyboard became disconnected from iCue. The keyboard did not reconnect with iCue until I restarted iCue, and restarted the keyboard.
I turned to online search: https://help.corsair.com/hc/en-us/articles/14066443517709-How-to-Fix-K100-Air-Firmware-Update-Wireless-Issues-with-5-12-76
I followed the instructions here exactly as they are stated, unplugging any unnecessary peripherals and turning off all unwanted software etc. Similar problems occur here where iCue doesn't even claim 'Update Failed" because it usually just boots the keyboard off iCue entirely. Although it did seem to successfully put firmware 5.9.68 on my device and NOT succeed at getting 5.12.76 on the device.
In the user manual it states you can reset the device by holding 'esc' while turning on. While this flashes my keyboard lights slightly, it does not return my firmware back to 5.11.xx.
Again I found these instructions online : https://forum.corsair.com/forums/topic/185213-k100-rgb-air-wireless-firmware-update-51380-installation-loop/
Also unsuccessful, but not sure if its because I can't get 5.12 loaded on the device.
I have a support thingy with corsair, but it is a bit too slow for me as its been 1 week and I only get responses 48hrs after I respond.
Also at times the keyboard disconnects from iCue and I have to quit it, and restart the keyboard... its a drag.