I was trying to create Mari-mekko chart in tableau by following steps mentioned in the link
http://www.tableau.com/about/blog/2016/8/how-build-marimekko-chart-tableau-58153. However, i was not able to get labels for some stacks even though there was enough space.I tried text wrap but it is not working.
Could you show us where you're selecting "on wrap"? Tableau typically doesn't support text wrapping so I don't believe it's supported.