The problem with being able to turn on and off and manipulate the Spec Tree is this. Sometimes it just 'Disappears'. It is there but you can't see it or you have minimized it and it is out of reach. How do you fix it?
There are a few ways to fix this.
1. Make sure the Spec tree is on by selecting View -> Specifications and ensure that it is Checked On.
2. If it is On try this. Make the Spec Tree active. To do this you will need to turn off the Geometry by selecting View -> Geometry. This will uncheck it. Then select 'Fit all In'. This should Bring the Spec Tree from the unknown.
or
3. Same as 2 only select the XYZ Reference Axis in the lower right corner. This will under intensify your Geometry making the Spec Tree Active. Then select 'Fit all In'. This should Bring the Spec Tree from the unknown.