Hi Swamptooth ... I missed the part where you asked about the high pass filter so I tried it and did a screenshot. It does show something there ... but it's around -110db and it shows up on the other filters too.
Have you tried the 'Auto' function on the Cakewalk Analyst ... it is frickin' cool! :)
Throw the Analyzer on a track ... enable 'Auto' on the Analyzer, enable Automation Write 'W', hit play ... and watch the show.
It scans the audio of the track you have it on and creates envelopes at the frequency ranges it detects.