I first tried connecting my Rift S to my other gaming machine which connected flawlessly. At that point I knew it was not the hardware that was an issue but software.
I then tried uninstalling the Intel(R) USB 3.0 eXtensible Host Controller - 1.0 Microsoft from the Universal Serial Bus Controllers in device manager and rebooted the computer which automatically re-installs the host controller when booting up.
This has sorted out the issue and everything is working fine now. I would surmise the issue had been a corrupted host controller file - although it stated all working when i checked prior.
Maybe offer this "fix" to others experiencing the same problem.