How to check images or objects
1) Check that you have descriptive text either as Alt-Text, a Caption, or information in surrounding text or an appendix.
2) If you are using Alt-Text, right click and select Format and the option for Picture, SmartArt, object, shape, or chart, and under Layout & Properties, check that the alt text box contains a description that states the purpose and/or function for meaningful images or objects OR that a “double-quote, space, double-quote” has been entered for decorative objects.