Nearly 1,200 workers at four Boston hotels, including the historic Omni Parker House, have gone on strike in the third wave of labor actions this month. Represented by UNITE HERE Local 26, the workers are demanding higher wages, fair scheduling, and safer workloads. The strikes follow months of stalled contract negotiations and come after the expiration of workers’ contracts on August 31. This labor action is part of a larger, nationwide dispute that began over Labor Day weekend and has seen 2,500 hotel workers from 12 Boston properties walk out. The hotels remain open but services are limited. Union leaders warn that more strikes are possible if their demands are not met.