Charts that are open on program startup don't show anything after simulation

If you have charts open when you start up the program, they won't show any relevant info even after simulation. Reproduce:

1. download the model below and import to sysdyn
2. activate experiment and simulate
3. open chart named "chart"
4. restart sysdyn with the chart still open
5. activate experiment and simulate again
6. observe how nothing is drawn to the graph, most likely due to the fact that "mice" stock symbol doesn't show/have any values attached to it BasicTutorialCompleted.sysdyn