By default Cubit only creates “edges” on the boundary of the model. So, doing a “draw edge all” only draws surface edges, or doing quality only checks boundary edges.
If your model is not too big, you can have Cubit generate those interior edges by issuing the command “set fullhex on” before you create/import the mesh. Then, you have edges everywhere including the interior at the cost of using a lot more memory. For example,
Bri x 10
Mesh vol all
Quality edge all length global ### Only checks the boundary edges.
Reset vol all
Set fullhex on
Mesh vol all
Quality edge all length global ### Checks all edges including interior ones.