Copy pasting from host to guest and vice versa is not working on NixOS 20.03. It was working on 19.09. My host system in MacOS; VirtualBox Version 6.0.16 r135674 (Qt5.6.3)
I’ve set all of the below in my configuration.nix
nixpkgs.config.allowUnfree = true;
virtualisation.virtualbox.host.enable = true;
nixpkgs.config.virtualbox.host.enableExtensionPack = true;
The associated dropdown in the settings pane (“Shared Clipboard”) is set to “Bidirectional”.