Revit project you see blue grips or arrows at the ends of the instance elements.
When setting out geometry from a Level in an elevation view, sometimes the Shape Handles (Grips) don’t appear. Why? I have no idea, but I found the solution by adding a reference plane on top of the level line and locking them together. Dimension to the reference plane instead of the level line and the shape handles appear correctly.
In the example below I used Generic Wall Based Family which has a Reference Level at the base of the wall. I’ve added a vertical sweep constrained by a reference plane at the top. The Height Parameter is dimensioned from the reference level up to the reference plane and is an Instance.
Note: Some Families already have a reference plane hidden along the same line as the Reference Level so check first to see if one exists and then make sure you dimension to the plane not the level.
Other reasons for not seeing shape handles appear are due to a string of instance parameters being joined together i.e. There are too many variables for Revit to work out which parts can be dragged/stretched!