Done some more looking into this. Turns out it only happens when:
System is booted without external monitor connected, then made to sleep, connected to external monitor while sleeping, then woken.
If the system is originally booted while connected to the external monitor, then it can be connected to an external monitor while sleeping, and this problem will not occur.
Done some more looking into this. Turns out it only happens when:
System is booted without external monitor connected, then made to sleep, connected to external monitor while sleeping, then woken.
If the system is originally booted while connected to the external monitor, then it can be connected to an external monitor while sleeping, and this problem will not occur.