When you load a simulation without the client, then the server process will be running but you will not be able to see what the server is doing or be able to change any properties. To connect to a running simulation, launch the workspace and then click on the tab of the Servers window of the Explorer pane. This lists all servers (simulations) that are running locally.
Selecting the node in the tree will display the server process properties in the Properties window (the bottom left of the workspace if it has not been customized).
If the Client Host and Client User properties are empty (as shown above) then that server process does not have a client connected to it and you may connect.
Do this by right-clicking the server process node in the Servers tree and selecting Connect from the pop-up menu.
The simulation will be opened in a new simulation tree in the Explorer pane.
If you select Connect when you are already connected to that server process, the window of the simulation tree will simply be brought to the foreground.