tl;dr the command-line solution to run inside your Linux VM:
sudo pkill -fx "/usr/bin/VBoxClient --clipboard" && /usr/bin/VBoxClient --clipboard
Background / Details / Synopsis
Now and again, copy & paste functionality can break between a Microsoft Windows host and its Linux guest VM (Virtual Machine) when using Oracle’s VirtualBox.
Symptoms include not only the inability to paste text, but also application freezes/lockups. For example, we found that Google Chrome on Windows became unresponsive for ~1 minute, when trying to paste text that was copied from our Linux VM, but would return to normal after.
A solution that works for us is to restart the VirtualBox Guest Additions inside the Linux VM, discussed here: How to restart Guest Additions?