Hello - just wondering if this issue has been resolved? I'm also having the same problem. I have the Statistics and Machine Learning Toolbox and MATLAB2017b, but the ranova function is undefined as well. Oddly if I do "help anova1" the anova1 function is defined so I know some of the stats functions are there, but ranova is not.
This link suggests that it is available in Matlab 2017b with the Stats toolbox: https://www.mathworks.com/help/stats/repeatedmeasuresmodel.ranova.html