@Stefan Schippers I am trying to plot the noise density of a PMOS device. NSD plots fine however when I set the y-axis to dB to plot looks good when I initially select dB in the waveviewer, but after I hit apply it dissappears and gives the output as shown (plot = onoise_spectrum):

Go in the graph, position the mouse close to the left of the Y axis and do a full zoom (f key)

Nice! Thanks @Stefan Schippers.