I tested and was surprised that this is exactly what happened, since it’s not been my experience. I entered some chords from Tone Sets, typed a few more, went back to Tone Sets and found the last search saved, and everything was hunky-dory. However, as soon as I put some notes in the melody, Tone Sets went back to the behavior I’m used to. Here’s a video:
This also happened when I opened a blank project, entered a melody, then tried Tone Sets. It always defaulted to a single note and never remembered my last search, even in a bar that had no melody: