I can't create line breaks.

Thank you as always. I am using Windows 11 and Thunderbird 153.3.1esr. When I open past newsletters using "Edit as New Message," I cannot create a line break by pressing Enter before the first character of the body text. Line breaks work elsewhere in the body text and in regular new emails. This mainly occurs with group newsletters. If I change the formatting to [Paragraph] and then switch back to [Body Text] with Ctrl+Z, I can create line breaks in that editing screen. Is there a permanent fix?