The error is with the initially tuned PID Controller. When launching the PID Tuner Application, an initial controller is tuned using default settings and the 'form' and 'type' specified in the PID Controller block.
For example, the type could be 'PI' and the form 'Ideal (Standard)'. However, the initial controller that is determined has a Proportional gain equal to zero, which can not be represented using Ideal form.
To get around this issue, change the form from 'Ideal' to 'Parallel' in the PID Controller block(s) and launch the PID Tuner App.
