On occasion you will notice that when you export your .smg file and preview it, it will have created a SOLIDWORKS Composer black background. This is obviously not ideal. You will generally only see this happen when you are exporting and have colour region turned on. There is a workaround for this!
Go to File > Preferences > Advance Settings, then scroll down to Hardware and enable the HardwareSupport.SilhouetteShader setting.
You will need to restart SOLIDWORKS Composer for the setting to take effect.