Given that I have been unable to reproduce this issue, a possible workaround I have identified would be to connect the output of the “PS-Simulink Converter” to the “Scope”, check “Log Data to workspace” under the Logging tab and select “Save format” as an Array.
Run the model, and the logged data would appear as an array with 2 columns. Using the “fft” function and “bar” function, calculate the Fourier transform on the second column of the logged variable and obtain the bar plot. If the variable name is ScopedData, the second column can be accessed using ScopedData(:,2).
Use the “abs” function to obtain the magnitude of FFT. Note that "fft" returns a 2-sided spectrum.
The documentation for “fft” is here, for “abs” is here and for “bar” is here.
Hope this helps.