Solution
The channels of this card will have polarity and that polarity cannot be inverted due to the diode that is the body diode of the FET, which is shown in the channel schematic:
In normal operation (like in the example configuration) the diode is connected in the following way: Positive to channel and negative to COM, which will cause that in an open connection the diode is reversed biased and it will not conduct, but if that polarity is inverted, when it is required an open connection the diode will be forward biased and will conduct.
Also, the FET opens and closes based on the gate-source voltage, so if the polarity is inverted it will require a higher voltage value to close the FET.