Sometimes when recording the source: Display Capture, the preview screen (and the finished video recording) only seem to refresh when the mouse is moved. Eg: When right clicking on your desktop screen saver, the drop down context menu only shows on OBS preview when the mouse is moved at least a pixel from its position.
So if you're recording and the mouse is not being moved, nothing happening on screen will show up in OBS preview, it just looks like a still image
So if you're recording and the mouse is not being moved, nothing happening on screen will show up in OBS preview, it just looks like a still image