Hi Mivision,
Greetings from Syncfusion.
We have ensured your reported scenario with attached sample. By default, PointColorMapping is used for data points with single series. When multiple series are used, default palette colors will be applied for each series.
In your attached sample, there are 4 series with each series has single point. We suggest you to specify the required color for series Fill property to achieve your scenario.
Kindly revert us if you have any concerns.
Regards,
Durga Gopalakrishnan.