Alarm list not showing on HMI

Hello Colleagues,
We are operating and maintaining a 5 x GE Frame 9e, Mark VI Control System, all units are online, but unit 1, 3, and 5 are not showing alarm list below the Simplicity screen in the PEEC as well as the central control room HMI, But everything shows on the engineering HMI.
what could Possibly be the problem?
what could we possibly do to get the alarm list to display again on those affected HMI's?
A few more Clarifying questions. What is your PC? Are you using ControlST/WorkstationST? What version of cimplicity? If you are using Mark VI with ETCSS and an HMB file, then for some reason the cimplicity to TCI connection has failed. I would start with Cimplicity's Status Log to find out more.