I misremembered and I thank all who've written to jog my memory. The bogus hour-long adventure show — the one I mentioned in this post, the one that never existed — wasn't an eighties' spin on Mission: Impossible. That show was produced and did exist. What I was remembering was the claim that a studio had secretly produced an updated version of the old Mr. Lucky TV show with John Vivyan and Ross Martin. That one never existed.
Which raises two interesting questions: Why hasn't someone produced an updated version of the old Mr. Lucky TV show? And why hasn't someone released the old one on DVD?