From my testing, the bug you described doesn't seem to pop up in the other presets I made using similar code. But those presets included code for a piece called the Heavenly Tetrarch, which wasn't allowed to skip the second part of its igui move. This piece does not exist in Chu Shogi, so I removed that part of the code when making the preset.
[Edit] This bug is now fixed. The lines that told the code to exit the do loop early after passing the second part of a double move were placed too far in. In the other presets, they were in the correct spots, but I had forgotten to update their position after deleting the code preventing the Tetrarch from passing its igui move in the Chu Shogi preset.
From my testing, the bug you described doesn't seem to pop up in the other presets I made using similar code. But those presets included code for a piece called the Heavenly Tetrarch, which wasn't allowed to skip the second part of its igui move. This piece does not exist in Chu Shogi, so I removed that part of the code when making the preset.
[Edit] This bug is now fixed. The lines that told the code to exit the do loop early after passing the second part of a double move were placed too far in. In the other presets, they were in the correct spots, but I had forgotten to update their position after deleting the code preventing the Tetrarch from passing its igui move in the Chu Shogi preset.