I've recently changed my SSD and thus I had to install a fresh copy of Win10 x64. After installing the OS, I've also updated the BIOS version to the latest one (v 1.40). One or two days later I observed that the FN key is not working anymore (although it was working just fine before the upgrade and the OS fresh installation). Hence I tend to believe that the key itself is ok and that it might be something wrong with the drivers. I've also reversed the mode of the function keys in BIOS and all of them are working (modify the brightness of the screen, modify the volume, etc).
Any suggestion on what might be the root cause of this behavior and how can I get is solved?