Hi Steve, you were right, the images in the footer were not outputting the alt tag, even though I have specified them in Media Library. (They say, alt=””.)
I went to the footer section in Widgets and selected the images in question. They had blank alt fields. I filled them in and cleared the theme cache. Inspecting the images in the browser, the alt tags are now being output.
However, hours after, the Image Empty Alternative Text warnings persist. Any ideas?
