Cimplicity HMI Won't Stop - PM_MCP

I have a GE HMI running Cimplicity. When I try to shut the project down in the toolbox, I get a message that says PM_MCP has control of the server and I am not allowed to shut it down. This has never happened before.

Any idea?

PM_MCP is the Master Control Program that co-ordinates all the CIMPLICITY processes. It can be controlled from the project using the start and stop buttons or from the CIMPLICITY Options app. It could also be that CIMPLICITY is still starting. Check what other applications are running to see what has control. These could be on another computer. Worst case, kill the w32rtr process and other CIMPLICITY processes will all stop.
When I try to stop the project, Cimplicity gives an error message that states PM_MCP has control and will not stop. Even after it has been running for more than a day. This application has been running properly for several years (with an occasional computer reboot). This is a dedicated control server. No other things are running. No other software has been added/upgraded.
What is the exact message? If you see "Cannot stop project. PM_MCP is currently controlled by <MACHINE_NAME>" then this means that <MACHINE_NAME> has control, typically from a Workbench instance or by CIMPLICITY Options. Another possibility is that the user that PM_MCP is running as has been changed and this user no longer has access to other CIMPLICITY processes. I suggest you contact CIMPLICITY tech support at GE Digital.
My comments might be too late, and you hopefully have solved the issue. I will agree, this is frustrating to get cimplicity errors. They tend to be very decrypted and don't shed a lot of help on the root of the issue. Try force rebooting your PC and then get the HMI back to running conditions. Start and stop Cimplicity a few times. If you don't get another error, then it could have been cimplicity project getting stuck in some process. If you still get the error, then we need to take a deeper dive. Let me know where you get and we can keep digging.