URDF Importer and Articulation Trouble

Hi, I am having trouble importing my URDF with the appropriate physics and joint constraints. I have made a camera gimbal model and exported the model as a URDF using a solidworks to URDF. Then, when importing the URDF to Isaacsim, I am able to see it, but when I simulate it, the physics do not work at all. The gimbal always shifts to the same angle and gets stuck there and does not abide by the physics. Note: the baselink (top mounting bracket) is fixed for this model.

The gimbal before looks normal (I would put a picture but cannot since I am a new user).
No matter the starting orientation before the simulation starts, here is the gimbal after:

I have confirmed it is not a problem with the model. This is probably a simple problem, but I have not been able to get it to work.

All help is appreciated!

Here is another example of where clearly the physics are wrong:

The top mounting bracket is fixed in space but the gimbal arms defy gravity.

please can you share the USD file, so that we can take a look how the simulation looks like?