4.0 not displaying text field changes

[Kee Nethery]

This kind of thing worked fine in 2.9.x but does not in 4.0.

I've got a new 4.0 stack that has a bunch of repeat loops within repeat loops. For a small example:

repeat with w = 1 to 1000
  repeat with x = 1 to 1000
    repeat with y = 1 to 1000
      repeat with z = 1 to 1000
        put "A" && w && x && y && z into field "status"
      end repeat
    end repeat
  end repeat
end repeat
put "A done" into field "status"

I'm not seeing field "status" change while it goes through the loops. What's up with that? I don't have any lock screen commands in the script. 

Is there some environment variable I'm supposed to set to have the field contents be displayed while a script is running?

Suggestions welcome.
Kee Nethery