"Network Error": Windows 7 VM Can't Access Files on Mac Host Machine (Mojave)

I have Parallels 18 Pro for Mac and use it for a Windows 7 Ultimate virtual machine.

I have not been able to access any files or folders on the virtual machine's host Mac computer (iMac i7 with Mojave 10.14.6) from within Windows 7 since upgrading to Parallels v18 almost six months ago. It always flashes the same error: "Windows cannot access \\Mac\Home\Desktop. Error code: 0x80070043"

This virtual machine (.pvm) is about 4 years old and I used to be able access my host Mac and my entire home local area network from within the Windows 7 VM under earlier versions of Parallels. I've tried changing every setting and restored to default with no luck. I've reached the limits of my own limited computer/networking knowledge.

* I really need to access the host & other Mac computers in my production studio from this Windows virtual machine. *

Can someone please advise what might be the best course of action for me to take? Thank you in advance!