Grails plugin dependency pulled into maven cache, but main project can't resolve classes - grails

Question

Using Grails 2.5.4
I have a plugin that uses the Twilio SDK (7+).
The plugin packages without error.
When I run the main project it throws an error saying that the it
cannot resolve the import com.twilio.Twilio class in the plugin
controllers/services.
I confirm that the Twilio SDK has been pulled into the local Maven
cache when the plugin was pulled in, so it knows to get the dependency.
The main project BuildConfig includes mavenLocal() in the dependency
resolution.
Where do I look next to find the cause of this dependency resolution problem?
plugin dependencies.groovy
grails.project.dependency.resolver = "maven"
grails.project.dependency.resolution = {
// inherit Grails' default dependencies
inherits("global") {
// excludes 'ehcache'
}
log "warn" // log level of Ivy resolver, either 'error', 'warn', 'info', 'debug' or 'verbose'
legacyResolve false // whether to do a secondary resolve on plugin installation, not advised and here for backwards compatibility
repositories {
grailsCentral()
// uncomment the below to enable remote dependency resolution
// from public Maven repositories
mavenLocal()
mavenCentral()
}
dependencies {
compile 'com.twilio.sdk:twilio:7.8.0'
}
in plugin.xml
<dependencies>
<compile>
<dependency group='com.twilio.sdk' name='twilio' version='7.8.0' />
</compile>
</dependencies>
In main project BuildConfig.gorrcy
plugins{
compile ":twilio-ext:1.0"
}
running grails dependency-report I see
org.grails.plugins:twilio-ext:1.0
But it has no sub dependencies listed.