HP ProBook 455 G5 function keys mapped to same scancodes

[ryuo@xxxxxxxx]

Hello. My HP ProBook 455 G5 has an unusual problem where some function 
keys are mapped to the same scan code sequence and hence to the same key 
code. It is only the brightness up, the brightness down, and the 
microphone mute keys that are effected. All others function as expected. 
I originally reported the issue to the downstream bug tracker at Ubuntu, 
which you can find here: 
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1784008

As I have exhausted all other known possibilities, I think the nature of 
my issue is somehow related to the HP laptop platform drivers. I would 
appreciate any guidance on how I could further debug the issue or 
assistance with a resolution to the issue. Thank you.