Thanks for considering Aspose.Slides.
It would be helpful to investigate if you provide more details about the scenario. For example, if code is not working with a particular table in a presentation, provision of such presentation will be helpful for us to identify the issue. For understanding purpose, I have attached the presentation that was created as a result of the code which creates a 3 x 3 table, adds some text to the first column of the first row of the table and further sets some font properties. The code snippet is as under:
Presentation pres = new Presentation();
Slide sld = pres.GetSlideByPosition(1);
Aspose.Slides.Table tbl= sld.Shapes.AddTable(50, 50, 1500, 250, 3, 3);
TextFrame tf= tbl.GetCell(0, 0).TextFrame;
tf.Text = "Column1";
tf.Paragraphs.Portions.FontBold = true;
tf.Paragraphs.Portions.FontHeight = 10;
Hope this will be helpful. In case of further inquiry / confusion, please feel free to share with us.