Is there any changes to Data Grid properties in LiveCode 7.x?

Question

In a stack which was already successfully used to built an iOS standalone (with Livecode 6.7), I need to get some data grid properties (such as the dgFormattedHeight or the dgHilitedLine).

The group script is:

on mouseUp
  if item 2 of the mouseloc <= the top of grp "myEvents" + the dgFormattedHeight  of grp "myEvents" then
    put the dgHilitedLine of group "myEvents" into tLineNr
    goToEvent(tLineNr)-- this handler is in cd script
  end if
end mouseUp

However, since I have recently upgraded from Livecode 6.7 to 7.0.5 and now 7.0.6, these properties are still obtained without any problem in Livecode, but are returned empty in the iOS simulator (version 8.3).

I have checked also with the much simpler script:

on mouseUp
   answer "Height="&the dgFormattedHeight  of grp "myEvents"
   -- or: answer "LineNr="&the dgHilitedLine of grp "myEvents"
end mouseUp

and the result is empty so that I only get "Height=" or "LineNr=" !

Any idea about the reason of this problem ?

My Livecode is installed on a MacBook Pro under OS X 10.10.3, with Xcode 6.3.2. Standalone settings in Livecode: Build for iOS, iPod and iPhone, 6.1 or later ("Build 32-bit slice only" is not checked).