Unfortunately there is no such a feature in our charting solutions. If you are using a DateTimecontinuousAxis you can work around this by using an extra series. The first series will show the positive data and the second will show the negative data. This however requires splitting the original data and inserting extra items. Also in order not to show the point marks for the extra items you need to use a template selector.
I have attached simple project to demonstrate this. The code I have provided is for guiding purposes and you need to update it as needed.
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