Had this issue with Kali and Debian. After a day and a half, while downloading an ISO for Ubuntu just to try, I found that open-vm-tools isn't enough for clipboard operations, apparently. You also need open-vm-tools-desktop, which is NOT included in the default VM image. I wouldn't be surprised if Mint running in a VM is similar.
# apt install open-vm-tools open-vm-tools-desktop
For the sake of future searchers, let me know if that worked.