I am using Aspose.Cells.dll for .Net version 7.0.3.0 to generate text file from the excelbook. If the excel sheet contains only shape collections, it is generating the empty text file. It is not extracting the text in the shapes.Please find the below code to generate the text file.
Now open the saved txt file into notepad, you will see a blank file. Aspose.Cells does the same thing. So, in short, this is not possible, i.e. convert Shapes or its text to be saved as txt file.