Disable any external FPS Limiters that you may be using.
Due to the way MiniMeters handles rendering on Windows using external FPS Limiters can cause issues when using multiple pop-outs.
Open Nvidia Control Panel, go to Manage 3D Settings, and disable Max Frame Rate.
Open your AMD Graphics settings and ensure that Frame Rate Target Control is disabled.
Open Nvidia Control Panel, go to Manage 3D Settings, and disable Background Application Max Frame Rate.