I found this old post and I am having this problem now. I have used the marquee to "catch" the model I want to move. I zoom into the reference point which is highlighted with a tick (corner of a wall) and click on it. I then click on the point I want to move it too, and... nothing.
I have tried holding down the mouse and dragging, and same thing, nothing.
Tried right click, move & drag and it just selects that object.
ArchiCAD 18/Windows 7/16GB Memory/i5 3.2GHz Processor/NVIDIA GeForce GT 610