PDF export from a page that contains Code Block macro does not displayed properly when it is previewed in another page as an attachment

Issue Summary

On a Confluence page, attach a PDF document where this PDF document is exported from another page that contains Code Block macro.
In the resulting preview, the page containing the Code Block macro will appear to be blank.
Clicking on an empty space on the seemingly blank page preview, and then dragging down (to mimic text being highlighted) will reveal that text does exist, but is completely transparent, and therefore unreadable.

Environment

• Confluence 7.4.11 + OpenJDK 11.0.13+8 (MacOS)
• Chrome 96.0.4664.55
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Steps to Reproduce

1. Create a page with some text and code block macro in it (you can use this storage format with Confluence Source Editor as an example: storage_format.txt)
2. Export this page as a PDF file by using >"Export to PDF" functionality
3. Create a new page and attach the exported PDF file to this page by using "Insert files and images" button.
4. Save the page
5. On the view mode, click the attachment to preview it.

Expected Results

Each of the pages should have a visible/readable preview.

Actual Results

The preview for the page which contains the Code Block macro will appear blank, but it does have the original text that's completely transparent/invisible. Please see the below screenshot:

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available.