ADS1015 gives strange output

I am using two ADS 1015 to read from 7 potentiometers - one ADS1015 with cluster of 4 potentiometers and the other with 3. All are working correctly except one potentiometer (from within the cluster of 4) - its output remains within a small band/variation unless I move the other potentiometers - only then this output changes to full range. I constructed two different such sets and the same thing happens. has anyone encounter such problem before ? - i.e. the ADC output of one of the potentiometers depends on the values of other inputs?

An additional note - I am using single-ended mode to read the absolute values from each potentiometer, not the differences across inputs.

Sounds like a wiring error to me. But it's hard to say, as you forgot to provide basic information about your project such as a schematic drawing of your circuit, nor the sketch you use (it could be a programming error as well, of course).

Post details of all the hardware, your schematic, and your code, otherwise there's no way to help.