Hi,
We have analyzed your issue further.
We have tested using the project you provided but we do not find any issue for chart data points. Please check the attached file ZIndex aca3a8d5-7653-4b69-a824-47cea24d3e60_open_in_excel2010.jpg. Even we did not find the points to zero in the file Aspose+picture_WaterMark.xlsx you provided. Please check the attached file Aspose+picture_WaterMark(You provided)_InExcel2010.jpg. We only logged an issue i.e., "CELLSNET-42723" for thinking the chart being splited to 3 parts in multiple pages. By our further analysis, the chart’s width is too wide so you are getting this behavior. You must set the sheet fit to one page to prevent the chart to be splited on multiple pages.
Thank you.