Welcome to the Blazor feedback portal. We’re happy you’re here! If you have feedback on how to improve the Blazor, we’d love to hear it!>
Thanks for joining our community and helping improve Syncfusion products!
In Polar and Radar Charts, when multiple series have the same data value at a specific angle, their data labels overlap. This creates visual ambiguity, making it appear as though only one label is displayed.
For example, at the angle corresponding to the year 2006, both series have the same value, and their labels are rendered on top of each other. This gives the impression that one label is missing when compared to other angles like 2005, where labels are clearly separated.
Sample: https://blazorplayground.syncfusion.com/hNBosZiwASTKbkNm
Screenshot: 
Reproducing steps: