A group too small to share out has fewer than 64 draws (2 x CHUNK_DRAWS), so a threshold of 64 or more never matched
in group_start and the setting did nothing. The setting's range is now 0..63, the menu's slider ends at 60 in steps of
4, and a value of 64 or more from nx2navi.ini reads as 63 with one line in the log.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>