Function of SubProject Script is not saved on MainProject button properties

Function of SubProject Script is not saved on MainProject button properties

Hi all,
I have created Main project with SubProjects. For some reason I cannot save Subproject a function link in the Main_Nav button to execute a script of subproject. After I close the Main_Nav screen and reload in Engineering Studio, the function link disappears set to default. NOTE: Just after save the screen (without closing) and tried to start Service Engine, the button does not work too.

Do you guys have any issues like this?

1. Function 0 -> execute Script.
 

2. Script: 



3. The button_1 function resets to default link: <No function linked>


NOTE:
- I have tried to link to Main project function lets say function_1. The function_1 executes the script of Subproject.  Did not work.
- Also tried to link to Main project function lets say function_2. The function_2 executes a script of Subproject, which executes a function in Main, and the function executes Script. Did not work.
- Also tried to import the Navigation Screen with Button link from XML, and start Service Engine straight away. Did not work too. 

In other words, I configure does not save the link.