What you describe should work for Preview/Print/Save as PDF.
Things that might make it fail:
an object along side or below the portal that is not also set to slide up/resize enclosing part. This could even be a graphic object such as a horizontal line.
Extending the size of your portal until it crosses the line into your footer. (And this is what you have here). Make the body longer to keep the portal inside the body.
Records that are present in your portal but not visible due to the fields in the portal all being empty for that record.
Yes. Increasing the Body size fixed it. Though I couldn't adjust the Body size by dragging: I had to enter numbers in the Inspector.
If you hold down the correct key (Alt) in windows, you can drag a part border even when a layout object crosses that line.