I printed v17, but still had a similar issue with the highest notes. I can still get more than an octave which is remarkable for such a small 3D printed ocarina! Of all of the 12 hole ocarina's I've printed this is by far the most consistent in terms of reproducible prints and tonal quality. It can consistent'y hit the low A and B and the flats and sharps come out nicely.
I have a few ideas that I am working on. First, I am slowing my inner wall print speed from 100mm/s to 60mm/s to see if that has an effect. Second, I also plan to print it upright instead of horizontal. Third, I merged both v13 and v17 together as I was comparing the stl files. I'm playing a bit with the left thumb hole size as it seems overly large compared to other sopranos. Finally, I am planning to do some tests with water and filler material. I've noticed with larger ocarina's that dipping them in water makes the tonal quality so much better (until they dry of course). Initial water tests, literally drown out these sopranos, so this may not be as effective given the size.
Monoprice Maker Select v2.1