Behaviours method selection field does not show by default after upgrade

Summary:

The field where you choose what method in your behaviour script file you want to run fails to show for existing behaviours that already had a method selected after the user has upgraded to Scriptrunner 6.2.0

Steps to reproduce:

1. Make 2 methods in a file in the default script root directory using the Script editor. It does not matter what the methods do
2. Create a behaviour with an initialiser and a field-level script
3. Add one method as the method for the initialiser and the other methods for the field level script method. (it does not matter what field)
4. Save the behaviour, and map to a test project
5. Navigate away and then back to edit that behaviour, check the method fields are still present.
6. Upgrade Scriptrunner to 6.2.0-p5 (current latest)
7. Refresh the page and edit the same behaviour. The method fields will be missing
8. Put your cursor in the file select field and add a space, then delete it. The method input field will the re-appear with the correct method

Outcome:

Method fields appear to disappear after upgrading scriptrunner

Expected result:

If there is a selected method in an existing behaviour, the method selection should not be hidden by default.

Notes:

I checked the XML endpoints shown here and they show the correct data so the error appears to be with the front end