With reference to this article:
To Hub Spot panel:
In the above article, please mention that images sent in replies from contacts will not appear as attachments if sent as inline images (drag and drop into text).
Rationale:
It’s important to know this, as if looking just in the attachments in the sidebar, it might look as if the contact has not provided the required document and this may affect the way we interact with them, or the way we handle their record.
Interim solution:
My current solution is to add a brief reminder in the template email asking for documents, that images must be attached as opposed to added inline.
Hope that helps!