Welcome to the ROG forum.
Have you installed Armoury Crate? You can update the firmware through Armoury Crate.
You can also try resetting your keyboard by pressing and holding the Fn + ESC Keys for 10-15 seconds.
I'm having the exact same issue but I noticed that my battery is swelling after a little over a year and a half of use. I believe that the battery swelling is causing the issues with the keys at this point since the issue has now spread to the asdf row and the qwerty row. My Claymore II is now FUBAR. Last time I'm getting a wireless mechanical keyboard.
Edit: I have already uninstalled the driver from device manager and all the software things even trying it on another computer with barebones install (aka driver) and no dice.
UPDATE: After further investigation, I disassembled my Claymore II and saw that the vertical connector was partially disconnected due to the swollen battery. I removed the battery, reassembled the keyboard, plugged it into my computer utilizing the wired connection and it works! All keys are now working without issue!
TLDR: Swollen Battery was causing the issues with keys functioning. Remove battery and keyboard still works! Granted, this fix does remove the purpose of it being wireless. I'm sure there are replacement batteries that can be purchased somewhere.
Hope this helps anyone who has these issues.
Edit: found battery model and you can purchase it.