What do grayed-out STOP and PAUSE buttons indicate?

What do grayed-out STOP and PAUSE buttons indicate?

The model was successfully updated in about 3 minutes. I've waited up to an hour for simulation to complete and then given up and stopped Matlab in Task Manger.

Trying different global and local solver options and keeping track of my trial solver settings. However, I wonder if the grayed-out buttons indicate more than just a slow/inefficient simulation.

Thanks,

Jeff