From what I can tell, you're asking why the size of the Comments field doesn't drop down to just one line? (that's the question I'll answer; tell me if you actually intended to ask a different question).
The thing that usually stops parts from resizing is some object, perhaps not visible, but certainly not set to 'Hide when printing', being off to the right. In layout mode, scroll off to the right, and use the selection tool to select everything (going to 75% or 50% zoom might make this easier). It could be a box with the fill color set to White, it could be a button, but I'll bet you'll find it there, about 2-3 inches below the top of the Comment field.
You have a merge variable in the footer. Is there any chance that it touches or crosses the line between body and footer? That might interfere with the slide up. You might make a copy of this layout and see what happens on the copy if you delete that object from the footer.
You were right on! I had a field off to the right and not in the print area. I often do this during development but didn't realize it impacts sliding objects. Thanks for your help.