In the Web Designer, I can create OhlcSeries but I cannot find a way to provide the OHLC marks. Whatever I enter for Y value, in the Design view I see the error "The XML serializer cannot resolve type with name: Telerik.Reporting.OhlcMarks". In Preview the error is "An error has occurred while processing Graph 'graph1':ohlcSeries1: OHLC values value cannot be null or empty when using NumericalScale".
If I created an OHLC chart with the Standalone Designer and opened it in the Web Designer, the Y value would display "[object Object]" as seen in the linked screenshot.