Each report, irrespective of the product is designed for a specific export type. 

For example, Risk Heatmap report is designed for PDF. 

If you want to export the report to any other export type such as Word or PowerPoint, you have the option of exporting the report to those types through the dropdown available. All these options could possibly work but the report is neither optimised nor developed to cater other options. Thus this may result in certain limitations in the report output with respect to formatting, alignments etc.

Below image depicts the different export types available:

In a situation where you need the Risk Heatmap report to be in PowerPoint format instead of PDF, we will have to accommodate that requirement via a new custom report that will be designed for PowerPoint.  

Note: As SSRS is a third party tool, we are not able to control the visibility of the other export options.