Strategic Priority - Problem Statement

Which of the core problem statements is the single most important problem/issue/challenge/opportunity for Starbucks to address or resolve? Clearly explain why this is the strategic priority for the company. - 400 words Problem Statement: Starbucks hasn’t been able to maintain customer loyalty due to its change in its loyalty program. Here is one link about it. https://www.inc.com/chris-matyszczyk/starbucks-has-a-major-problem-it-may-have-just-made-it- worse.html Need another link or two that focuses on loyalty.