Describe the bug
When I add an image to a markdown widget and then edit as Markdown. Switching back to "Rich Text" means the image disappears. This seems to have crept in in release 3.8.0. 3.7.2 is fine.

To Reproduce

1. Add an image to a markdown widget
2. Switch from "Rich Text" mode to "Markdown" mode
3. Add some text in Markdown mode
4. Switch back to Rich Text mode

Expected behavior
To still see the image in the editor, along with the Alt Text and Title fields

Screenshots
Markdown mode:

Rich Text mode after adding some markdown:

Applicable Versions:
v3.8.0 onwards

CMS configuration
Here's a simplified config I have replicated the issue with:

backend:
  name: test-repo
  repo: *****
  use_graphql: true
  squash_merges: true
publish_mode: editorial_workflow
media_folder: "static/images/uploads"
public_folder: "/images/uploads"

collections:
      
  - label: "Use cases"
    name: "use_cases"
    folder: "content/use_cases"
    create: true
    slug: "{{title}}"
    fields: 
      - label: "Title"
        name: "title"
        widget: "string"
      - label: "Challenge"
        name: "challenge"
        widget: "markdown"
        buttons: ["bold", "italic", "code", "link", "quote", "bulleted-list", "numbered-list"]
        required: false

Additional context
Thank you!