Jay-Z’s latest concert at Yankee Stadium hit setbacks after fans noted tech failures . The crowd lingered after their phones lost connection. Some screens turned off mid-set. An actor stood in for Mary J. Blige after she faced a last-minute problem . Teyana Taylor stepped in later to assist. Blue Ivy Carter played piano for part of the show. Dame Dash then stated Jay-Z’s recent stadium gigs felt more like product demos than genuine concerts.