Apparently I’m not alone in struggling to get Mint to run under Hyper-V.
Fix 1 – Make the mouse cursor visible: Open a terminal and run the command:
gsettings set org.cinnamon.settings-daemon.plugins.cursor active false
And that’s all one line, regardless of funky word wrap.
Hat tip to the commenters on: https://www.technig.com/install-linux-mint-on-hyper-v/
Fix 2 – Running in software rending mode
This thread on linuxquestions.org led me to install MATE via instructions from https://winaero.com/blog/how-to-install-mate-in-linux-mint-cinnamon-edition/
In a nutshell, run this as root (you’ll need to sudo su first, sudo alone doesn’t seem to cut it):
apt-get update && apt-get install mint-meta-mate
And then log out and back in with the MATE desktop.