@Sumo,
in last updates for Windows 11 in some regions Microsoft added Copilot application for users. Unfortunately KPM 23.1.0.192 has conflict with it when trying to copy password to clipboard.
We will fix it in 23.2.0.* release next month. Till the new release of KPM you can use the following workaround:
Go to Taskbar settings in your Windows (Personalization -> Taskbar)
Turn off the Copilot option
Reboot your PC
You may encounter a similar problem when using third-party applications that monitor the clipboard. For example: VirtualBox, Punto Switcher, Download Master.