Is Starbucks’ mobile app the company’s greatest weakness?Former CEO Howard Schultz has said as much, per a recent podcast appearance. And it’s something new CEO Brian Niccol will likely tackle first when he takes the helm at the coffee chain next month, CNBC reported Sunday (Aug. 18).According to that report, both investors and executives have blamed operational troubles for the company’s lagging sales, with Schultz telling the Acquired podcast earlier this summer that the mobile app is a problem, calling i ...