Please make sure that you are running the latest versions of the MainWP Dashboard (4.3.1.), the MainWP Child plugin (4.3.1), and the Clone Extension (4.0.3).
Lastly, can you please post the community system report from your MainWP Dashboard for review? The report is located in your Dashboard under Info → Server, on the top right of the page.
Be sure to use the button like the one below; this button hides all your private information:
Pressing the button auto-copies the report to your clipboard then just paste it in a reply here.