Embedded CID font is shown as blank in PDF preview

Problem Definition

CID fonts which are embedded in PDF file are shown as blank in PDF preview.

You can see this problem with the following steps to reproduce.

1. Attach font-test.pdf to a Confluence page
2. Preview the attached PDF file

This PDF file consists of the following contents and the each line is written with the corresponding font.

As each font is embedded in the PDF file itself, you can see that the second line with "IPA Gothic" font in the PDF is previewed as expected even if the corresponding font file is NOT installed in Confluence server.

On the other hand, the third line and the fourth line with “Hiragino Kaku Gothic” Font (CID) are not shown correctly.

Suggested Solution

It would be better if CID font is rendered correctly as well in PDF preview.

Note:

Have tried installing the CID fonts in Windows and getting the following error as it is incompatible:

CID fonts are unable to be installed on other platforms. Therefore, the only possible way is to allow Confluence to render the CID fonts in the PDF preview correctly.