Basically what the title says. When the you deactivate the automatism of an object, it deactivates automatism for all. Even when I create an event that activates an object, if there is at least one object that has deactivated automatism, it still won’t work.
I’ve tweaked the Physics.gdg example to activate or deactivate the physics automatism when I click on on a floor with the left or right mouse button and everything works well: 
togglePhysics.zip (295 KB)
I can’t seem to open that in GD. It says one or more extension isn’t available. BuiltInObjects. Here is the bug recreated: dropbox.com/s/khwe2ih5agu9i … G.zip?dl=0
Which version of GD are you using?
I’m assuming the latest stable version cause when I hit check for updates, it’s saying the same version number: 3.3.71.0