This appears to be the case because the system needs more time to create all of the data points, and then the figure would show all of the simulation data. This would not be an issue if sufficient time is allotted to finish letting the scope update.
To confirm this, or as a workaround:
1. Check the "Save data to Workspace" checkbox under the Scope block properties.
2. Rebuild the model.
3. Complete the external mode run and wait until the simulation completes and the scope has data updated.
4. Click on the "AutoScale" button from the Scope block to view all the data.
You may also want to consider setting the "duration" to a larger number.
