I wondered about that too. Since that's one that Randy directed he must have had some input. I think they just ran out of time. I enjoyed seeing them together in the Fall Guy episode ( The Lucky Stiff) and the Malibu Fire episode of Diagnosis Murder. Johnny seemed so concerned about Dr. Brackett when Brackett was hit by the drunk driver in Loose Ends.
I thought that since the accident happened in the middle of the night or late at night that Dr. Early & Dr. Morton were on that shift and maybe Brackett wasn't there cause he was on the day shift at the hospital. Usually when you see Brackett & Dixie it is during the day! Love that episode!
But I think I remember reading that Robt. Fuller was in contract negotiations when that eppy was made so that's why he's not in it. And I don't remember a reason given on the show for Brackett's absence.