You have the startpoint of the Depth parameter at the grip that you want to move. Changes in the properties keep the Startpoint constant and change the length of the parameter by stretching the end point. To fix it, rotate your parameter 180 degrees, delete the current stretch and add another one that is associated with the end point instead of the start point. It can be visually helpful to set the grip display to 1 if you are only using 1 grip. That way if the grip you want to use disappears, you know that you have your parameter backwards. It also helps with block editing in more complex blocks.
I attached your file in an unfixed state (learning happens best from doing), but with an additional stretch action added to the other end of that parameter so the grip shows up and you can see what is happening when you change the properties.
