I am currently facing an issue with an HP laptop running Windows 10, whereby the following keys are not responding at all when typing: R, T, F, G, V, B.
Sticky keys and other similar features have been turned off.

Any fix for this issue?

The next test I try is to see if the issue follows with some USB PC Keyboard.

However the keys are in what looks like a few scan lines of the common matrix decoding so it looks like a hardware issue from here. What about the number keys? 4 and 5 here may fail too.

I have repeated problems with Dell Hardware Support in trying to convince them that a problem is hardware (warranty) rather than software (not covered). I have found that the easies way is to boot into Linux and demonstrate that the problem still exists. Download a Linux (I find kubuntu the friendliest) LiveCD and burn a DVD. Bott into the DVD (select try instead of install) and see if you have the same problem. If you do then you know the problem is with the keyboard.

To Reverend Jim. On Dells we have Dell Diags (varies with model) so try this. Boot the Dell and hold down the D key. See if there's a keyboard test.

Most Dells these days do come with a diagnostic partition that yu can select if you tap-a-tap-a on the F12 key while powering up. I think POWER+D just boots into a special (undocumented) video diagnostic. Can't say if HP has something similar.

@Reverend Jim - Tried booting with a linux live cd, still got the same issue with the same keys. Number key 5 however is giving something bizarre on Windows however when typing on notepad, it starts a loop with the full date and time and stops only when I press the "Enter" key.
Will try to test with a usb keyboard and revert back asap.

USB keyboard working well. So indeed it's a problem with the matrix itself it seems, and thus a change required...