ScriptRunner Behaviour and Hidden Custom Field

in my Resolve Screen on a Transition I want to have a Custom Field (Fixed in Release) only shown when Resolution=Done and only for one project - until here that works fine:

import com.atlassian.jira.issue.resolution.Resolution

def ResolutionField = getFieldById(“resolution”)
def FixedInRelField = getFieldByName(“Fixed in Release”)

def Resolution = ResolutionField.getValue() as Resolution

if( == “Done”) {

} else {

But I want to have this field hidden for all other projects.
So when I hide Fixed in Release in the Field Configuration Scheme the ScriptRunner Behaviour doesn’t work anymore - Fixed in Release is never shown even if Resolution=Done.

How can I achieve that Fixed in Release is always hidden and only shown in one project when Resolution=Done ? And therefor I want to use only one Workflow.