That sounds weird.
Can you give us some more details on exactly what's happening?
What version of JMP are you using? What are you trying to drag and drop? Which part of the drag and drop operation is failing, the drag (i.e., you can't pick up what you want) or the drop (i.e., it won't go where you want it)?
Do you get an error message? Is this happening with all Graph Builder platforms or only after you've built a specific graph?
I know this post is old, but I am facing similar problem today. It was working fine and suddenly I have lost my ability to drag & drop in graph builder. So when you click on variable and try to drag it, it does not work. Instead you get a hand symbol which when you take it near axis, it shows message click here to place the variable. Its find for since x & Y parameter but no option if you want multiple varibles on Y axis. I tried mulitiple time restarting JMP, but no luck.
When I right click on Y axis (before placing any varible) and trying to click on properties, it gives and error for JMP exception and crashes. I am using JMP 12 from server.
Any help would be great.