Proportional editing is not applied on the first click when you have a huge clip view in your 3d view.
You have to use the mouse to change the size of the influence a little bit, then the proportional editing gets applied.
You can test with the following settings :
clip start : 1000
clip end : 1000000
object dimension X : 15000
object dimension Y : 16000
object dimension z : 1700