The attached MPP file does not save as PDF with Aspose.Tasks for NET 20.6, instead it seems to hang the process (have left it for 30 minutes) and use many GB of memory.
var mpp = new Aspose.Tasks.Project("input.mpp");
mpp.Save("output.pdf", Aspose.Tasks.Saving.SaveFileFormat.PDF);
I can replicate the issue of rendering process failing to get completed on exporting to PDF. A ticket with ID TASKSNET-4252 has been created to investigate and resolve the issue. We will share the news with you as soon as the issue will be fixed.