Thanks, this is a bug we’re aware of and we’re in the process of getting an update out for everyone. I’m very sorry for the alarm! This is a display issue only, occurring when the first character in the initial paragraph in the editor is reformatted (for certain character formatting); the text is hidden in the view but reloading the document in the editor or changing the editor view such as by adjusting the zoom will cause the text to reappear.
Thanks, MM. Knowing we can zoom the text back into visibility makes all the difference. No need to revert then; better to hang in and await the subsequent release. All best.