Try adding a new state to force the graph to resize.
I'm seeing a few of these reports recently and I'd like to get to the bottom of it.
What I think is happening:
While dragging states the graph size is temporarily expanded to make room for you to drag, when you stop dragging the graph shrinks back to fit the states. If this sequence is interrupted the graph can be left in an expanded state. I think this is what people are seeing when the FSM disappears or seems zoomed out.
One way I've been able to reproduce the problem is to move the mouse out of the Playmaker editor window while dragging and then close the editor or press play while still in drag mode.
This might explain the bug reports I'm seeing. Does this seem likely in your case?
But it seems a little convoluted.
Another scenario is that another editor script is pulling focus away from the Playmaker editor while you're dragging. This is more consistent with reports where the graph "disappears" while dragging states.
Are you using any other third party editor tools?
I'm currently investigating 2D Toolkit and Smooth Moves... are you using either of these?