I'm using the latest 0.9.0 release but the file generated from the Sample_05_Chart.php is broken and Powerpoint 2016 needs to repair the file before opening it (which removes the charts completly).

Sample_05_Chart.pptx

I've tried to validate the generated *.pptx file against Office 2013 XML formats and it throws 218 errors. Seems like every value for the attribute 'val' is a string having a percentage sign behind it instead of Int32