Got it, so it’s not just the keybinding. Input isn’t working in the second window at all. This is a known focus issue when moving Agent to another monitor.
After you move Agent to the second monitor, try reloading just that window: Ctrl+Shift+P then Developer: Reload Window. This worked for other users with a similar issue: Bugs in Agent/Chat window when its moved to editor and on different monitor
If reloading doesn’t help, let me know and I’ll pass it to the team.