Indeed. Thanks for following up. That pushed me to dig deeper. It looks like it might have to do with timing.
- If you only enter “Hello” into the title line of the PM and stop, a draft will be saved

- If you only enter “Hello” into the textarea of the PM and stop, a draft will be saved

- If you enter “Hello” into the title line of the PM and then immediately enter “Hello” into the textarea, no draft is saved

- If you enter “Hello” into the textarea of the PM and then immediately enter “Hello” into the title line, no draft is saved

When composing a topic, all of the above scenarios appear to work.