M1 GPU locks up when running Unreal Engine 4.26 games

This issue was introduced early in the Monterey testing path, and was not resolved by the stable release today.

Basically, any time I try to run either of the two Unreal Engine 4.26 based Apple Silicon games on my machine, either Apple Arcade's Wonderbox, or Cyan Worlds' Myst 2021 release, the GPU performance is horrid compared to Big Sur, and then within 10-15 minutes of gameplay, or on anything that would cause a GPU quality level change in Myst, such as enabling or disabling super scaling, the GPU locks up.

Within a minute of this lock up, both monitor outputs shut off. The machine continues to respond to VNC and SSH connections. However, under Monterey, the VNC connections produce no usable picture, so the session is useless.

The SSH sessions show that the machine is still responsive, but useless with only SSH. Attempting to sudo reboot just locks up before it can ask me for the user password.

Console logs on reboot show that WindowServer was being terminated once per minute due to watchdog timer expiring waiting for the existing instance of WindowServer to respond.

Filed FB9723369