Tag the Document
Check that tags were created correctly and are in the correct reading order.
Tags are the basis of an accessible PDF file. They indicate the structure of the document, communicate the order in which the items should be read, and determine exactly which items will be read.
If the PDF file was created using "Convert to PDF", tags should already have been created.

Use the Reading Order tool to see the existing tags. If there are no highlighted tags, run Add Tags to Documents.
Menu: Tools > Protect & Standardize > Accessibility > Autotag Document