Pivot view in 2.9, when using multiple-field breakdowns is using fixed width, and not auto-adjusting well to the actual number of values in a given row/column.
We have fixed this issue in the new version, coming with 3.0, in the next couple of weeks.
In the meantime, you can try switching the version (under the Pivot's Tools menu) to the older one, although that will limit you to a single field breakdown on both X/Y axis.