You had quite a lot of imgfile identifiers for those checkboxes? Most likely a result of a bug in the version you’re using. When i stripped them out things got better. Also note that two of the checkbox have the exact same positions and dimensions. This will confuse the editor when you click on one. If you need to have controls with the same position and dimensions work with them directly in the code. Anyhow, here’s an updated Cabbage section for you that should work:
<Cabbage>
form caption("LV-4000") size(500, 350), colour(43, 41, 41), pluginid("def1")
image bounds(0, 0, 500, 350) file("Main Texture.png")
keyboard bounds(34, 248, 435, 100) whitenotecolour(255, 255, 255, 255) keyseparatorcolour(197, 197, 197, 102) arrowbackgroundcolour(207, 207, 207, 255) channel("Key")
rslider bounds(38, 132, 93, 108) range(0, 1, 0, 1, 0.001) channel("sModVol") imgfile("Slider", "rslider.svg")imgfile("Slider", "rslider.svg")imgfile("Background", "blank.png")text("Voice Gain")
rslider bounds(36, 20, 93, 108) range(1, 4, 1, 1, 1) channel("sWave") identchannel("sWavei") increment(1) value(1) imgfile("Slider", "rslider.svg")imgfile("Slider", "rslider.svg")text("Wave Shape")
rslider bounds(168, 46, 150, 150) range(10, 35, 10, 1, 5) identchannel("sBPW") channel("sBPW") increment(5) value(10) imgfile("Slider", "rslider.svg") imgfile("Background", "blank.png")
checkbox bounds(360, 134, 68, 33) channel("stretchbutton") imgfile("On", "buttonin.png") imgfile("On", "buttonin.png")
checkbox bounds(392, 186, 68, 33) channel("distbutton") imgfile("On", "buttonin.png")imgfile("On", "buttonin.png")imgfile("Off", "buttonout.png") imgfile("On", "buttonin.png")imgfile("Off", "buttonout.png")
checkbox bounds(358, 56, 68, 33) channel("octbutton") imgfile("On", "buttonin.png") imgfile("Off", "buttonout.png")
rslider bounds(448, 134, 40, 40) channel("stretchamount") range(0.1, 1, 0.1, 1, 0.001) imgfile("Slider", "rslider.svg")imgfile("Slider", "rslider.svg")imgfile("Background", "blank.png")imgfile("Slider", "rslider.svg")
label bounds(360, 116, 76, 11) text("TimeStretch")
label bounds(360, 176, 76, 11) text("Distortion")
label bounds(168, 200, 151, 15) text("Bandpass Width")
</Cabbage>