We were able to observe this issue by executing your sample code with your source excel file using the latest version: Aspose.Cells for Java v16.12.3 and found that chart is wrong on opening and saving the source excel file.
We have logged this issue in our database for investigation. We will look into it and fix this issue. Once, the issue is resolved or we have some other update for you, we will let you know asap.
This issue has been logged as
CELLSJAVA-42128 - Chart is wrong on opening and saving the source excel file
I have also attached the output excel file generated with this code and screenshot highlighting for are a reference.
Java
Workbook wb = new Workbook(dirPath + “aaaa.xlsx”);