Cannot open preview when editing .ipynb with VSC notebook editor

[tjwieg]

Describe the bug
The button to preview works when editing my .ipynb file in the plaintext editor, but when editing the file in the notebook editor, the preview button does not appear in the editor/title menu.

To Reproduce
Steps to reproduce the behavior:

1. Open a jupyter notebook with VS Code's plaintext editor
2. Look at the title bar
3. The "preview" button is there
4. Reopen the same notebook with VS Code's native notebook editor
5. Look at the title bar
6. The "preview" button is not there.

Screenshots
Plaintext editor:

Notebook editor:

Desktop:

• OS: Windows 10 Pro, v1903
• Version:

Additional context
Add any other context about the problem here.