All android elements are placed at (0,0) in ConstraintLayout

If you are using ConstraintLayout you should be seeing warnings already on your elements.
Following is the warning Android Studio gives you.

This view is not constrained vertically: at run-time it will jump to the left unless you add a vertical constraint less... (⌘F1) 

The layout editor allows you to place widgets anywhere on the canvas, and it records the current position with design-time attributes (such as layout_editor_absoluteX.) 
These attributes are not applied at runtime, so if you push your layout on a device, the widgets may appear in a different location than shown in the editor. 
To fix this, make sure a widget has both horizontal and vertical constraints by dragging from the edge connections.

So basically you should make sure a widget has both horizontal and vertical constraints by dragging from the edge connections