This seems to be a (semi) long standing issue with FM8, in that others have reported having problems with it: to be specific, when pressing return, FM ignores the Next Tag information and adds another line using the same tag.
I ran into this issue last night. Since I didn't know that others had experienced it, I thought it was something weird with my installation and I reinstalled everything. Not something I really wanted to do! The Adobe Forums thread (http://www.adobeforums.com/webx?128@@.3c059165) hasn't been updated since April. I was wondering if anyone had found a fix or work around for this in the months since? -- Lin Sims