Hi @Laford, Thomas
This is indeed strange. I did a simple test and when setting the color of the empty points to Automatic, it doesn't seem to show the color.
I found this thread for you which simulates the color palette in an expression to solve the problem: https://stackoverflow.com/questions/39124724/automatic-color-no-color-for-empty-point-data-in-ssrs-report. Hope this helps.
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Best regards,
Aniya