The reason for this seems to be that professors from the various colleges teach courses for continuing education, but the courses are not supervised directly by the colleges of the various academic programs. So, just because there is no mention of an online course on the academic page, there may be courses listed at the continuing education site.

To find courses at a college or school that may not appear on the college page, find an active link on the page that directs you to the university homepage or "back track" the URL to and find the college, school, or division of continuing education.