What is the Issue?
The limited PDF export occurs when elements (such as texts or images) or their sub-elements (such as parts of groups or tables) are located outside the slide. If the message appears after the export, axesSlide could only process the slides listed there with a simplified PDF export, which may not ensure PDF/UA compliance.
How to fix it?
In order for axesSlide to process the slides correctly, delete all elements outside the slide or move them onto the slide.