Using the sample plugin code from http://download.macromedia.com/pub/developer/acrobat/sdk/dc/sdkDC_v1_win.zip
sample project Acrobat DC SDK\Version 1\PluginSupport\Samples\ExternalWindow there are certain pdfs that fail to open. It typically just shows a blank window, but they do open properly if opened in Acrobat DC without the plugin loaded. I haven't been able to find any visible similarities between pdfs that work and don't work.
Sample PDF
Any Ideas?