Course members have a "Subscribe to this forum" link in every forum for a course. It's not clear what this link does. The link's title attribute is, "Send me email copies of posts to this forum" and that is very clear, but the screen readers tested read either the link's text or its title, not both.
Why it matters
A blind user has a higher cost for failure than a sighted user, and might waste several minutes clicking a "Subscribe" link and figuring out what it does.
The link text should be clearer, e.g., "Receive email updates from this forum."