QR code is not displayed on back cover when PDF is generated via GitLab Pages pipeline

[hmsdoc]

Hi, I've noticed a problem where the QR code on the back cover is not displayed when the PDF is generated via a GitLab Pages pipeline. In this case the back cover is displayed as expected but the rectangle, where the QR code should be displayed, remains empty.

When I try it locally via Docker, the QR code is displayed as expected. I've used the exact same configuration locally and on GitLab. The console output of the GitLab pipeline did not show any errors.

Is there a way how to fix this? Are there any configuration parameters for the QR code?

Thanks in advance!