How to put new/blank lines between numbered list in macOS mail?

I recently purchased a 2025 MacBook Pro to replace my old 2019 Intel MacBook Pro (I forgot exactly which version of OS it was running but my guess it's macOS 12 Monterey). On the new macOS, I’ve encountered a few things that used to work on my older Mac but no longer seem so on Sequoia. One of them is not being able to add blank lines between items in a numbered list in the Mail app.

I’ve tried various combinations of keys (Return, Control, Shift, etc.), but none allow me to insert the blank lines I need. These blank lines are important not only for aesthetic reason (e.g. to visually separate items in the list) but also for practical reasons. For instance, when attaching images at the end of or between list items, blank lines ensure the images appear above or below the text. Without them, resizing the Mail window causes the text to shift around the image dimensions, making the email difficult to read.

Is there a new way or key-combo to do this, or has Apple overlooked such a simple yet important feature?