Using Jira expression to validate Affected Services during transition does not work

Issue Summary

The result will always be false when using a Jira expression similar to the one below to check if the Affected Services field is not null during a workflow transition, even if the field has a value:

issue.customfield_10041 != null

Please note that to use a Jira expression in a transition validator, the ScriptRunner app is needed.

Steps to Reproduce

1. Add the Affected Services field to a transition screen.
2. Add a "ScriptRunner Script" validator to that transition and add a simple Jira expression to check if the field is not null. For example:
   issue.customfield_10041 != null
3. Publish the workflow changes.
4. Go to an example ticket and try to transition it (set a value to the Affected Services field in the transition screen).

Expected Results

If the field is null then an error message should be displayed and the transition should not be allowed. If the field is not null, then the transition should be allowed.

Actual Results

Even adding a value to the Affected services field, the ScriptRunner validation with the Jira expressions will always treat it as null.

Workaround

Use the transition validation of type "Field Required Validator" that comes built-in in Jira. It works as expected.