If relevant texts or objects are missing in the Logical Document Structure in the PDF of your presentation, exported with axesSlide, check the following points:
Is the Element Marked as Decorative?
If so, uncheck "Mark as decorative" and export the PDF again with axesSlide. Find out more in Add Alt Text or Mark Object as Decorative.
Is the Element on a Slide Master or Layout?
If so, insert the element directly on the slide. Elements on the slide master or layouts are automatically exported as decorative by axesSlide. More on this in Slide Masters and Layouts.
Is the Text Rotated?
Rotated text is currently not supported due to a Microsoft error. Find out more in Text Formatting. Insert the object again without rotation and export the PDF again with axesSlide.
Are there Elements Outside or Partially Outside the Slide?
If elements are outside or partially outside the slide, axesSlide may not be able to process the slide correctly. The slide is then processed with a limited PDF export, more on this in Message "Limited PDF export". Make sure that the elements are completely on the slide and delete redundant elements outside the slide.