I encountered a case in which the Visual Editor gave a preview that was not as the final result looked like. It can be found in the edit: https://en.wikipedia.org/w/index.php?title=MicroMasters&diff=887780935&oldid=884550624
I was able to fix the problem in the this edit using the source code editor: https://en.wikipedia.org/w/index.php?title=MicroMasters&diff=887782970&oldid=887780935