Hi Adam,
here is the scenerio in FF:
1. copy the text from notepad.
2. Place the the cursor at first position i.e. before Approve and press enter then the cursor moves to far lower side in editor instead of moving the content to next line.
3. Other issue is when you press enter key before text having strong tag then the strong tag get removed.
I am able to reproduce it in your example also. Please have a look.
Thanks,
Sanjay