The reason I use Isaac Sim 4.2.0 is because there is a problem with version 4.0.0:
When I try to use the Action Graph to control the opening of a Kinematic Rigid Body object (whether it is Mesh or Xform), it will flicker back and forth between the original position and the position updated by the Action.
It seems that the update to 4.2 has perfectly solved this problem, but the Script Node has lost its function.
I tried copying the libomp140.x86_64.dll file from the 4.2 version back to the lib of Isaac Sim, which fixed the startup error. However, the flickering problem also came back!
I am sorry to hear that upgrading to the latest version has caused you so many issues. I am moving this discussion to the Isaac Sim specialists in the Isaac Sim channel.