I have a similar problem to this question: space between Crystal Reports Cross-Tab Column, but I'm pretty sure the gap is not caused by the page size.
In Crystal Reports (CR 2013), the cross tab displays just fine:
However, when I use the Crystal Viewer (SAP CR Viewer 2011), which my customers will have, there is a gap:
The page size should be fine, as the header fits fine. In addition, I have a different cross tab on the first page, it is wider, and it doesn't have the gap. The page size is set to landscape legal, no printer.
What other issues could be causing this?