Since you have upgraded from 6.2 - 7.1 ML8, Have you checked out the HTML5 readiness landing page available via Designer Studio -> User Interface -> HTML5 Application Readiness ?
Seems like your harness is rendering in non standards mode. Please go through the steps in the landing page to upgrade you harness to use latest HTML5 markup. Also there is a setting available in the application rule form to "Render in HTML5", please check that as well.
After the above changes rerun your scenario and let me know the results.