Able to use Built-in Script 'Copy Field values' to copy the third party plugin field value: Multi-level Cascading Select type to Jira standard select list (cascading)

As a user, I wish to use Built-in Script 'Copy Field values' to copy values from a third-party plugin supported custom field multi-level cascading select to Jira standard select list (cascading).

Steps to replicate:
1. Install Multi-level Cascading Select Plugin and set up a custom field (Categories) from this plugin (Multi-level Cascading Select type).
https://marketplace.atlassian.com/apps/5008/multi-level-cascading-select?hosting=datacenter&tab=overview

2. Setup list of values for options in Categories (setup at least 1 or 2 options with 2 Levels = parent + child value) e.g. Option1 > Option1A, Option 2, Option 3 > Option3A, etc.)

3. Create at least 1 ticket and enter the value for Categories.

4. Setup another custom field (Categories-New) Jira standard Select List (cascading) and create the same list of values for options as Categories (step 2)

5. Create a filter to be used in Scriptrunner > built-in script > Copy field values, at least it should return 1 ticket where 'Categories' is not empty.

6. Run the Scriptrunner > built-in script > Copy field values by selecting the filter ID setup in Step 5 and selecting 'Categories' as 'Source Field' and 'Categories-New' as 'Target Field'.

Expected Behavior:
It is supposed to copy the value from 'Categories' to 'Categories-New' after running the script.