Okay, more testing in my Linux VMs - copy and paste doesn't seem to work into Customize Display. Anyone else confirm? The clipboard is correctly copied from the host to guest VM, so that isn't an issue. However if I attempt to copy anything within MC (e.g song title, artist name, etc.) and paste that into gedit (all within the VM), it doesn't work.
I'll test from the native Arch install here in a few mins.
EDIT: Anything I'm writing into gedit/Text Editor then highlighting and copying via the right click menu works (and thus the contents are in the clipboard) however trying to paste said contents in MC via Paste from right click or CTRL+V doesn't work. Paste isn't selectable so it's not reading the clipboard.
EDIT 2: Okay, tested from the native Arch install and the results are the same. Copying from outside MC (e.g gedit) and pasting to MC doesn't work. Nor does copying from MC and pasting to gedit. However copying and pasting within MC itself seems to be working fine. So that's pretty much it here - I've confirmed this behaviour in the native Arch install, Ubuntu VM, Arch VM and Mint VM. I'll test the Debian VM here in a few mins, but I suspect the result will be the same.
EDIT 3: Same result with the Debian VM.