Koharu Rikka AI v123b1 producing unusual auto-pitch tuning results

I’ve been noticing some unexpected behavior with Koharu Rikka AI’s newest beta update (v123b1) when it generates Sing mode curves for standalone notes consisting only of vowels:

The note pictured is only A4, well below the point that Rikka’s pitch should falter, yet it drops drastically below what is expected. this issue mainly affects short notes, from the minimum note length to about ~3 quarter notes, and stops if within 1/2 quarter of another note, or if the lyric is replaced with one containing consonants (for example, the pitch curve for “ta” behaves exactly as expected.)
This issue seems unrelated to tempo (increasing and decreasing tempo did not generate an expected pitch curve) and seems to persist when using XLS as well.