Answered this on github, but for anyone else.
You can not update a panel's HTM using $().html() - this removes the scroller. You must use $.ui.updateContentDiv http://app-framework-software.intel.com/api/index.html#$.ui.updateContentDiv
$.ui.updateContentDiv("#firmList",'<div id="firmListInside"><ul></ul></div>');
Then you can access $("#firmListInside") no problem