Pie chart symbols not showing in exported pdf map

[PeteKnutson]

I have been unable to export, (using ArcGIS Desktop 10.3.1) a map showing pie charts.  When exporting to pdf, the pie chart symbols are not showing.  It's a small page size map with less than 10 pie chart symbols created from a point feature class and 7 numeric fields. Can this be done? Has anyone else experienced this and determined why it's happening?

[GarretDuffy]

I think it might have found what was causing the issue.  I had made the pie charts transparent.  When I removed the transparency, it rendered fine and at high resolution.  Then I applied transparency in Illustrator.

[AnnaBuchheit]

I have this problem too.  I have a large wall map (42in x 42in) displaying quite a bit of information and I am using pie chart symbology with label expressions.  At a scale of 1:300,000  and symbol size of 48 they were exporting fine as pdf.  When I made a second map at a scale of 1:700,000 and symbol size of 55, the pie charts no longer display in the exported pdf.  Every other symbology displays fine (and this is a busy map!).  The dpi is set to 150, CYMK and all that. Still tweaking it to see if the symbol point size has a threshold...

Like I said, the two maps are identical in page size and setup. One has a smaller scale than the other with a handful of more polygons but less line work.  The pie chart symbol is the only one that is disappearing upon export. There is no transparency on the pie charts...