Solution
This is expected behavior. To have a better understanding, refer to the
NI Product Documentation Center page on ni.com to check the acquisition engine state diagram of your oscilloscope/digitizer.
For the sake of simplicity, examine the below-presented
acquisition state diagram of the USB-5132/5133 oscilloscope.
As you can see from the diagram, configurations can be done while the oscilloscope/digitizer is in the idle state. Once the oscilloscope/digitizer gets armed and enters the wait-for-start-trigger state, it won't be responsive to the configurations.
Not all oscilloscopes/digitizers have the acquisition engine state diagrams, however, this principle applies to all NI oscilloscopes and digitizers.