The volume level in the plugin “Volume” does not properly translate the mouse coordinates when the graphical fader is moved.
Click or drag the fader above the halfway point and the value is too small. Click or drag below the halfway point and the value is too great.
Yes getting the same experience as you. Also, if i put the fader to 0 and then click the centre of the fader cap (The black horizontal line) it jumps to around -1.5.
In fact, that sharp jump isn’t at all good if you were recording automation.