Data relation of Lookup field broken

Data relation of Lookup field broken

I have a Lookup field ('Import Data') called 'Player_Entity' (on form A), for which I limit the choices available in the 'On Load' event with the following code:
  1. //Limiting Entity field choices to player
  2. tempValue = input.Player_Entity;
  3. clear Player_Entity;
  4. Player_Entity:ui.add("Himself");
  5. for each recPE in frmPlayer_Entity  [Player_Name == input.Player]
  6. {
  7.     Player_Entity:ui.add(recPE.Name);
  8. }
  9. Player_Entity.select(tempValue);
As you can see in the code, there is a field called 'Player_Name' on the same form (form A). There is a similar code in its 'On User Input' field to adjust the 'Player_Entity' choices.

The Problem:
It all works fine, except for that when I change the name of the Player_Entity in the Lookup fields target form (form B), the field Player_Entity on form A is not updated. I was under the impression that adjusting the selection of an 'Import Data' field should not break the data relation... Is this a bug?