Repository target and source branch variables aer empty

[goodnickoff]

I configured my plan to create a branch when PR is created in linked repository.

I'm trying to get source and target branches of the pull request bu variables are empty.

Here the script I configured as a task:

And here is a log of execution of the plan after PR created in linked bitbucket repository:

As you can see all variables related to the pull request are empty.

Could someone please help me with that issue?