I guess I will have to spend more time with this. I found that I have learned more of the fretboard with single note melodies, thus far, than chords. To me, chords are shapes, and I don't think of the notes within (yup, I know I totally should - was like that with piano, too), so this is a completely different thing that I have to work on, because it's absolutely alien (to me). Thanks a lot for your thorough and thoughtful suggestions in this thread.My suggestion is to take a break from playing single note melodies.
Focus on playing chords in first position. Then chords in other positions up the neck.
This will let your subconscious remap to where the notes are on the ukulele fretboard.