Okay, so I know next to nothing about Cinemax softcore, we don't get Cinemax in Australia so I've never seen it at all. Having said that, let's see if we can narrow it down.
You said 1986. So the film was likely produced in 1986 or before.
According to what I've been reading just now, Cinemax didn't air softcore series like Confessions until 1992, so we can rule out that series or anything after it.
Perhaps you might find some clues here:
https://www.goner-records.com/board/index.php?action=vthread&forum=4&topic=3575