To those of you following this thread, I can report that NCH has issued a beta version that fixes this particular problem. You can get it here:
https://www.nchsoftware.com/beta/wavepadmaci.zip
This is showing as version 9.02, but it is not a finished product. For example, when I try to Save a file? The program hangs and I have to do a Force Quit. Nonetheless, in addition to the fix to Find Peak, I am seeing some pluses and minuses in this version.
Pluses
The distracting window which shows all other NCH products? You can now close that window.
The program now seems to be more Mac compliant. When you double click on the edge of a window, the window now expands in that direction.
Minuses
The Playback controls have changed. You now have to to do Opt-P to start playback instead of Enter. Why?
You still cannot close or minimize the Playback Controls or File Info windows
You still cannot separately edit individual channels.