Jay-Z’s latest concert at Yankee Stadium hit setbacks after fans noted tech failures . The crowd waited after their phones lost connection. Some screens went dark mid-set. An actor filled 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 claimed Jay-Z’s latest stadium gigs felt more like commercial tests than genuine concerts.