Thanks for getting in touch. Attaching a crocodile clip to the Touch Board increases the capacitive load on that electrode which looks just like a touch that never goes away - hence the behaviour you describe! If you restart the code after adding the crocodile clip this will recalibrate to the additional static loading.
Another bit of useful advice is to keep the croc clips stable when they are attached - motion relative to one another changes the static capacitance too, which can cause false triggering. As always, restarting the code recalibrates.
Hope this helps!