Nick Petit

The problem you're experiencing with the pieces flying everywhere with the new builds isn't in the sim - if you dive inside the RBD Bullet Solver you'll see the sim behaving as it should.
There was a fix that was pushed out to address an issue with animated and deforming geometry not making its way into the sim - this caused a regression when no “deforming” attribute was found on the geometry. This has been fixed in 18.0.353

In the meantime, if you add a “deforming” int attrib on the incoming geo and set it to 0 should fix the issue, or making sure the input is not time dependent will work too.

It's doing what it should be doing - by making some pieces inactive, with the constraints, you're essentially holding the frame up in place, so it no longer collapses under its own weight. If you disconnect the constraints from the RBD Bullet Solver, you'll see the active pieces fall to the ground.

Here's a modified hip with a sphere falling on the active section of the frame which shows the constraints holding up the structure and then breaking on impact with the sphere.

Constraints don't affect the active/static state of the RBDs, and the RBD Configure SOP only adds bullet attributes.

If you have a hipfile showing the problem I can take a look.

Cheers,
Nick