by any chance did you forget to install the guest additions to the vm? that solves most problems i have run into. every time i seem to have an odd issues, i remember to install the guest additions and that fixes the issue. just a thought anyway.
yah my little trick works fine unless you want to save and share that data between systems. then it quickly is not good enough. another work around is that win 10 can actually mount a virtual hdd. i've done this a few times when i actually needed to get to a vm's files and did not want to revisit the sharing nightmare. it does have to be a vhd or vhdx file but from disk management you can mount one easy enough.
but for true easy sharing back and forth you're gonna have to figure out the sharing problem. i may have some time later to revisit the problem. if i figure anything out, i'll be sure to share what i learned
edit: as a quick test, i just created a new share folder in a windows and macos vm and it shared right away. i just sleected my entire data drive and set it to automount and make permanent and both vm's have the share no problem........ i do have guest additions installed for them all as i know that is required. first time it ever worked right away