I have managed to solve the problem.
It appears that Microsoft Teams (the replacement for Skype for Business), was interfering between Studio and Windows Audio. After resintalling Studio several times and removing and reinstalling the Windows Audio devices, I decided to shutdown Windows, disable the audio in BIOS, reboot back into Windows, disable Teams boot startup, reboot back into BIOS and re-enable audio and boot back into Windows.
Studio then started up without any errors and now I'm able to use Studio with Windows Audio at the same time as running other audio applications, such as Netflix/iPlayer/Prime streaming on Firefox. Fortunately, I don't need Teams on all the time.
I haven't yet tested recording but playback works fine.