Should have mentioned this has only happened after HP replaced the motherboard.
Update : found out why I'm (probably) having issues. The laptop was bought as a ZBook Studio G5. The motherboard that HP fitted, under business warranty, is from an EliteBook 840 G6. To say I'm raging would be an understatement 😞
Also found out that the system flat refuses to recognise the onboard speakers or microphone so i suspect that the new motherboard is not working as it should.
He did supposedly update the BIOS when he rebuilt the system.
I've raised another case for the speakers etc so see what happens.