Idea plugin doesn’t generate RUNTIME dependencies properly

The idea.module.scopes.RUNTIME.plus collection does not behave as documented here:
https://docs.gradle.org/current/dsl/org.gradle.plugins.ide.idea.model.IdeaModule.html#org.gradle.plugins.ide.idea.model.IdeaModule:scopes

The idea.module.scopes.PROVIDED.plus collection behaves as expected (adds an xml node to the .iml file with scope=“PROVIDED”) but when I put RUNTIME instead, it appears to have no effect whatsoever.

Possibly related to this issue: Idea plugin don't generate dependencies properly

I should specify that I was using the Intellij “import gradle project” feature, not the “gradle idea” task.

Gradle Version: 3.1 and 2.14
Operating System and JVM version: Windows, 1.8_45
Intellij 2016.1.3, 2016.2.2 and 2016.2.4
Is this a regression? Unknown

Please see an example project that demonstrates the issue