I went ahead and used 'Create Windows 10 installation media' option to upgrade VM to latest version of Windows 10 automatically whilst keeping personal files & apps intact. Upgraded from Version 21H1 to Version 21H2 for Windows 10 Pro: https://www.microsoft.com/en-us/software-download/windows10
Issues with using F5 to refresh folders, logging on, bringing up 'save as' dialog boxes in Windows all seem to be finally resolved! The same issue was happening on another local PC (non VM) except it was already on Version 21H2. Using same upgrade process also resolved the issue.
Chalkin' it up to a bug perhaps, or the upgrade restored some underlying functions in the OS. Hopefully this helps someone else out there. 