Intellij Idea 2020.3 Grails 2.5.2 Can not resolve symbol for Grails Classes

Hi,

I have started facing this trouble, probably since the last update. I have an in place Grails plugin that uses

import org.codehaus.groovy.grails.core.io.ResourceLocator

Even though the project runs fine, Intellij is not able to resolve this symbol and there are such reds all over the place. I have re-imported the project as well after cleaning up all caches, removing .idea folders etc. But nothing worked.

Any help is much appreciated.