We use font extension and include the jar-file in the Java build path for some reports to embedd the font in PDF-files finally.
Since Jaspersoft Studio 6.8.0 (CE) the PDF-preview of reports within the studio(!) does't work anymore, java-preview still works.
Using Studio 6.6.0 (CE) with the same workspace still works, too.
The error message tells the font could not be loaded, but it exist, and works <= studio 6.6.0 (CE).