To add clarification, I'm not hitting any default of 10 limit. I'm already using limit=100 in my report.
Probably a complete splunk diag from all indexers, search heads, and forwarders in your environment will help us diagnose and advise you.
From the 'real estate' comment it sounds like you're talking about the FlashChart's legend not showing all of the series values?
Assuming that's the case, I cant think of a charting.* key that will allow you to compress the legend entries. That's not to say there isn't one.
You can always make the FlashChart physically larger of course, in which case I know that it will definitely show more entries.