It was a non-issue, Trumpers drank the vitriolic scapegoating kool-aid because it's who they are, they can't help it.
The CIS is not an impartial center. Their goal is to reduce immigration and thus their studies bias towards that. As the Newsweek article states he started reducing the number around then. Btw - notice how immigration wasn't a main national issue until Trump brought it up on his campaign trail and it resonated with voters as xenophobia has throughout history.