This bug exist in Wavelab 8, I did not upgrade to 8.5 because of the lack of the multichannel wave support. When this is supported by Wavelab, I will resuscitate my Wavelab installation.
However, the bug may exist also in the version 8.5, so I report it that someone can check. When in the Spectral view, and using the vertical zoom, it is not possible to Scroll up or down through the zoomed spectrum when the logarithmic view is selected. Please correct this bug.