The default Asset Allocations report shows percentage for each investment as long as the graph is displayed. (BTW, why only 10 items + 'Other' - there is plenty of space for more)
The percentages are missing if the graph is not displayed.
The percentages are not shown with the report because they are part of the graph. It would be nice if there was a percentage column in the report.
To see your asset allocation as percentages, you can go to the Investing > Allocations tab. If you click on Rebalance Portfolio, you can see and print the "What is Rebalancing" page.
One annoying issue with this page is that Actual and Target graphs both show the segments in largest to smallest order, so the segments are often in a different order, making comparisons difficult.
Have you defined custom asset classes? How many? With the seven default classes, the chart shows them all