If you drag an element in a section or in 3D to a different story, the Home Story of the element won't be adjusted. So, it can happen, that an element is located on e.g the 1st story but it has a different Home Story. (To avoid issues like that use 'Edit Elements by Stories' or 'Copy/Paste')
If you want to fix that by changing the Home Story to the correct one in the Selection Settings Dialog, the chair will be elevated:
It happens because the 'Bottom Offset to Home Story' is constant and to preserve this value, the 'Bottom Elevation to Project Zero' has to be adjusted.
If you want to change the Home Story without changing the element's vertical position, select the element and go to Edit / Element Settings / Relink Home Story.
Select the required story from the list and click 'Ok'. All the height values remain unchanged, the element won't be lifted, it will keep its vertical location.