Provide only relevant details required to explain the setting oh this case: The union that represents more than 1,500 health-care workers, including LPNs and RCWs, says many of its members are being denied their vacation requests. Karen Jackson, president of the Union of Public Sector Employees, said the union has filed a grievance, after Health P.E.I. failed to post members' vacation time this month, as set out in their collective agreement. Jackson said they were told the vacations couldn't be posted on time because of staff shortages. "Our members are pretty disappointed," Jackson said in an interview with CBC News. "I mean, they've really had a rough time, especially the last two-and-a-half years during COVID, making sure that their clients are well cared for and like I said, doing the heavy lifting for Health P.E.I. on the front lines," said Jackson. "And they really need a break. They need to be granted their vacation so they can get the necessary downtime that they deserve