How to access jenkinsfile local environment variables from post steps? - jenkins-pipeline

Question

I'm attempting to add a post-build step to my jenkinsfile to apply a label to a build. The Jenkins variables are resolved fine, but the environment variables I've defined globally within the file are not resolved. Here's the relevant bits:
pipeline {
environment {
VERSION_MAJOR = '1'
VERSION_MINOR = '0'
VERSION_PATCH = '0'
}
stages {
stage('Build') {
steps {
echo('Testing p4Tag')
}
}
}
post {
success {
build job: 'Copy-Installers',
parameters: [
//
string(name: 'MASTER_VERSION_MAJOR', value: '${VERSION_MAJOR}'),
string(name: 'MASTER_VERSION_MINOR', value: '${VERSION_MINOR}'),
string(name: 'MASTER_VERSION_FEATURE', value: '${VERSION_PATCH}'),
string(name: 'MASTER_BUILD_NUMBER', value: '${BUILD_NUMBER}'),
string(name: 'COMPONENT_NAME', value: 'Console')
}
}
}
The downstream build fails. Looking at the log it appears the local environment variables are not passed in:
The Build Number name is: ${VERSION_MAJOR}
The Build Number name is: ${VERSION_MINOR}
The Build Number name is: ${VERSION_PATCH}
The Build Number name is: 924
The Build environment name is: Console
Update
I've tried the following variations as well:
value: '${env.VERSION_MAJOR}' - Fails similarly to above
value: '$VERSION_MAJOR' - Fails similarly to above
value: $VERSION_MAJOR - Fails with "no such property" error
Update 2
For what it's worth, these variables can be referenced from the stage section. For instance, this works as expected:
stage('build') {
sh('./Build/build-package.sh $VERSION_MAJOR $VERSION_MINOR $VERSION_PATCH $BUILD_NUMBER')
}