I want to take some text and have it wrap around the edge of a circle, with the top of the letters toward the center of the circle. Using a pair of tutorials (curve text, circle with text), I have gotten text to do this. However, there is a weird bug in how it calculates text wrapping; it uses only about 3/4 of the circle before wrapping to a second line. The two minimal-difference examples are below; one uses 169 pt font and the other 170 pt.
Ideally, this text would wrap around the entire circle, with only slightly more room between the end and the beginning than between words. I expected that by slowly adjusting the size, this could be accomplished, but it jumps suddenly. What is going on, and how can I fix it?