SampleMPPFile.zip (69.8 KB)
Please refer to attached MPP files created with aspose tasks version 18.6 and 18.11, when you check the finish date 18.6 shows as expected where as 18.11 its completely broken, you could even check the gantt chart displayed.
Can you cross check and let me know what is changed between 18.6 and 18.11 in handling the duration with manual options.
Program.zip (925 Bytes)
Program.zip has the sample set of code which am using in my actual project, if you run this code with 18.6 and 18.11 you should be able to see the difference in behavior.
Note: I see similar behavior with 19.1/19.2 as well.