Image not rendering when email body of LN source has MIME Content Type: multipart/mixed

We are migrating a Lotus notes mailbox to a SharePoint list.

When we migrate an email body  with property "Content-Type: multipart/mixed" , The inline images are not displayed in the body.

The images are attached to the SharePoint list item but is not displayed in the body html.

The images are also missing when email is migrated to a MSG file or PDF file. I can't attach screenshot due to data restrictions.

I raised Service Request # 4744073 but the resolution provided is https://support.quest.com/kb/233955 which is about folder structure of a mailbox.

Do any of you have encountered this issues when the body of the LN mailbox is  Content-Type: multipart/mixed ?