Execution of a Call-task operation inside a function-unit depends on its Step/Combine Mode property, while Studio hides this property as non-applicable
How to reproduce:
In an online task, create a Control-Verification-unit and a Function-unit.
In the Control-Verification unit add a line with a Call SubTask operation and set it's Mode property to Step.
Copy this line (Ctrl+Shift+R) inside the Function unit
Note that the Mode property is now invisible. Still it's Step value is retained,plus it will be respected on runtime.
Try to execute this function in Fast mode (e.g. when exiting the task): the subtask will never execute
How to fix:
Copy the line back to Verification-Unit, so that the property is visible.
Change the Mode property to Combined
Copy back to Function unit.
Notice how now it works.
The line containing the Call operation was not typed. Instead it was copied to the Function-section from the ControlVerification section.
In the ControlVerification-section the Call operation had the Mode attribute set to Step. When copying this line to a Function-section, XPA hides this Mode-attribute, so the user cannot see or edit it any more. Still it is obviously retaining the hidden Step value, and unfortunately during runtime it respects it.
The fix is to delete the line and to hand-type exactly the same. In this case XPA obviously set the the hidden Mode attribute to Combined
(This issue has been also reported to MSE problem-submission)