Background Images Missing From Emailed Certificates

Summary

When emailing Learn certificates upon course/assignment completion, the HTML background image is missing.

Content

Hello,

We have created 2 certificates in Learn that are mapped to learn plans and set to be included in the email to the user upon completion of the learn plan. When receiving the PDF attachment in the completion email, we noticed that the background image of the certificate is not appearing for some reason. Initially we thought the issue might be related to the "print background images" option in the print settings, but it appears that the attachment itself does not have any background image data as if it is being stripped out when being generated/sent from Learn for some