To reproduce:

• Eg go to "Visitors => Custom variables"
• Select "Pivot report" via cog icon
• Open any other report
• Go back to "Visitors => Custom variables"
• It says the report is pivoted but it is not

Problem: The HtmlTable visualization is applied instead of PivotBy because there is no URL parameter that says "pivot is used" here: https://github.com/piwik/piwik/blob/2.16.0-rc1/plugins/CoreVisualizations/CoreVisualizations.php#L46-L50

The decision which visualization to use is made later by saved ViewDataTable parameters but we have to decide which of those two visualizations we want to use earlier. To solve this we need to give Pivot visualization a unique name (Visualization ID). This sounds easy but it is not that trivial since we somehow still need to disable HtmlTable visualization in such a case. There must be better solutions :)