Board Thread:Questions and Answers/@comment-178.116.134.44-20161030195025/@comment-31798553-20170421231535

Maybe try after saving all sqm in MCC, exit the editor, then open that SAVED mission and delete all and paste new like you are doing. Don't forget to SAVE and don't rename it.

Just a guess, thinking its not taking cuz the fille is still open in the editor.

Hope that makes sense.