As you know, there are two options in archicad to collaborate with maxonform - The "create new object" and "edit selected object"
First one is to make a new element in maxonform. If you choose that, all of your work will be transformed in maxonform but will be half-visible and non-editable. You'll have to make new elements in maxonform.
In second option you can select object (in 3d window, archicad) and edit it in maxonform. All your work will be again transformed and half-visible except selected object - this one will be fully visible and editable.