Inline images are not displayed

[GergelyKalmar]

I'm using the attach_inline_image_file functionality of Anymail (see https://anymail.dev/en/stable/sending/anymail_additions/#inline-images), however, the inline images don't seem to appear properly in the debug toolbar's mail panel (neither in the body or as an attachment). The inline images otherwise work fine when sent and viewed with a regular email client.