A picture here would really help. One thing to keep an eye on is that changes to the shape kick in at the start frame only. So ensure you rewind all the way to whichever frame your Maya timeline is starting at in order to see the change.
From there, you should expect a Box shape to not show any triangles. That’s a sure-fire way of knowing the change kicked in and that it is editable as a box.
Another thing I noticed is that you may have picked Assign instead of Assign and Connect when you assigned to your controls. What the Connect part is important if you want your controllers to stay connected like in your rig, otherwise I expect they would independently fall to the ground.
Can you share which version of Ragdoll you are on? It’ll say towards the bottom of the Ragdoll menu, and you should ideally be on 2022.07.20.
Here are some examples.
https://user-images.githubusercontent.com/2152766/193765727-f4bf806a-2ddc-4cfe-8bcd-f49d873475c1.mp4
In this first one, notice that my controls do turn into box-like shapes, even though they are Shape Type = Mesh. And also notice that they do self-collide, which is why it odds that the shapes in your previous thread did not already collide. Then notice how the triangles disappear, and how I’m able to edit the shape of the box now, via the Extents attributes.
In this next one, notice how I instead use Assign and Connect. By letting Ragdoll know that you want your controls to be connected, it won’t look at the NURBS CVs anymore, but instead look at the hierarchy of your controls and default to giving you Shape Type = Capsule, with the root of the newly created chain being animated - a.k.a. Kinematic.
This is what I expected you should see, when you assign to your controls.
https://user-images.githubusercontent.com/2152766/193765734-91cdec22-a191-49f7-a86b-2bccbf2ed2dd.mp4
Finally, if you do want Shape Type = Mesh and aren’t happy with the boxes or shape sizes, this is where you can edit the CVs. In the case of assigning to a polygonal shape, rather than a NURBS control, you can edit the vertices of the polygons.
https://user-images.githubusercontent.com/2152766/193765744-33a89616-b5a2-4bea-8afd-90247faf2b5a.mp4
Finally, as it happens, a thread was just made showing the setup of a new character by @boricuapab that may help here:
Also if you haven’t spotted it, there’s an introductory video here.
Hope it helps, and please keep sharing anything else you stumble upon!