A quick update: I said that triplet entry worked fine on an empty bar. I misremembered - an empty bar has the exact same problem - I must enter a non-triplet note before the triplet entry will work.
Some answers to the answers: What I call the "Top buttons", Finale calls the "Main Tool Palette" Triplet problem: Assume that I have copied part of a voice to another. The copy contains one bar wit...