We’re looking into both of these issues at our end. Please spare us some time and you’ll be updated with the results accordingly.
The coordinate system of the attached sample input PDF file is usual Cartesian system. I tried to add a stamp in this file using latest merged version using coordinates (100,150) and it started from lower left corner and stamp was added successfully.
First off, please try to use the latest merged version (Aspose.Pdf for .NET 6.2.0) at your end. If you still find the same issue then please share the complete code snippet as well, so we could reproduce the issue using your particular scenario. Also, please provide the details like OS, .NET Framwork version, application type (Web, Windows, Service) etc.
We’re sorry for the inconvenience and looking forward to help you out.