Analog Switch cannot provide 0V output when OFF
The datasheet is not clear on this it guarantee's leakage current, but it stops short at 1V. There are no figures that would suggest the leakage decreases or increases, but I suspect that it would increase because the fet's cant turn fully off if the switch voltage and the Vdd voltage are equal. 

The leakage below is for 5V to 0V which is a similar situation as 8V.


Source: https://www.analog.com/media/en/technical-documentation/data-sheets/ADG1611_1612_1613.pdf