Greeter doesn't appear on external monitor after lock/suspend

## Prerequisites
- [X] I have searched open and closed issues for duplicates.

## Describe the bug

Running Elementary OS 5.1.4 on a laptop hooked up to a external monitor. I usually keep the laptop closed and use a external keyboard and mouse. Whenever Elementary goes to sleep or is locked I can't seem to wake it up without opening the lid of the laptop. During suspend it will turn on the lock screen.

A work around for me was to install gnome-screensaver instead and let it take over the lock-screen. That works fine with displaying output on the external monitor and waking from suspend.

### To Reproduce

1. Laptop hooked up to a external monitor.
2. Close the lid on the laptop.
3. Lock the screen/suspend the machine
4. Wait for the screen to go blank
5. Press any keyboard button to make the lock screen pop appear.
6. This won't work

Workaround is open the lid on the laptop and the screen will sync up and the lock screen will pop up.

### Expected behavior

Make the lock screen appear on the primary and only active monitor
## Platform Information


- [ ] I'm using the latest version from git that I've manually compiled
- [X] I'm using the latest released stable version