Correct reading order of dynamic content not determinable
The reading and navigation order MUST be logical and intuitive.
People who are blind cannot see when content is dynamically added or updated in a page. If content is changed above or in a location remote from a screen reader user's point of reference, they may never be aware of the change. Changes of content must be added, in the DOM, below the element or event that triggered the addition, or focus must be thoughtfully managed within the workflow. A screen reader user will then encounter the changed information in the natural reading order or work flow of the content.
Fix this issue by using ONE of the following techniques:
Ensure that added or updated content is, in the DOM, below the element or event that triggered the change.
Thoughtfully manage programmatic focus within the workflow so screen reader users are made aware of new or updated content without disrupting the user's overall workflow / reading order.