(The Center Square) — Employees at a Pittsburgh-area Starbucks say they want to de-unionize amid growing workplace tension. The request comes just one year after the Penn Center East location became one of 25 in Pennsylvania to organize under Starbucks Workers United, which is affiliated with the SEIU. Longtime employee and Shift Supervisor Elizabeth Gulliford filed a petition with the National Labor Relations Board, or NLRB, on July 12 to hold a vote on whether to break with the union. Gulliford supported the establishment of the union but changed her mind after she said its representation created tension at the...