See the below code. Bullets are shown in the PPTX file but not the PDF.
new License().SetLicense(@"Aspose.Total.lic");
var presentation = new Presentation();
var slide = presentation.Slides.First();
presentation.SlideSize.Orientation = SlideOrienation.Portrait;
presentation.SlideSize.SetSize(SlideSizeType.A4Paper, SlideSizeScaleType.DoNotScale);
var shape = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 10, 10, 300, 300);
var textFrame = shape.AddTextFrame(string.Empty);
textFrame.Paragraphs.Clear();
textFrame.TextFrameFormat.AnchoringType = TextAnchorType.Top;
var p1 = new Paragraph();
p1.Portions.Add(new Portion("This is some text."));
var p2 = new Paragraph();
p2.ParagraphFormat.Bullet.Type = BulletType.Symbol;
p2.Portions.Add(new Portion("This is a bullet."));
var p3 = new Paragraph();
p3.ParagraphFormat.Bullet.Type = BulletType.Symbol;
p3.Portions.Add(new Portion("This is another bullet."));
textFrame.Paragraphs.Add(p1);
textFrame.Paragraphs.Add(p2);
textFrame.Paragraphs.Add(p3);
presentation.Save(@"C:\Users\Paul\Desktop\BulletTest.pptx", SaveFormat.Pptx);
presentation.Save(@"C:\Users\Paul\Desktop\BulletTest.pdf", SaveFormat.Pdf);