I have incorporated a copy of the Gantt Chart Visualization into my dashboard, and it shows up and works great. However, if I schedule the dashboard for emailing a PDF, the Gantt Chart is not on the PDF. The titles for the panel are there, but no graphics. I find that this same behavior exists in the Gantt Chart Visualization Sample page with the documentation as well. Any ideas?
I'm afraid that's a problem common to all the Splunk custom visualizations, you can see it as well in Splunk's Dashboard Examples app (https://splunkbase.splunk.com/app/1603/).