"Could Not Fetch Model" error when converting project to Gradle using Buildship

When I try to convert an existing Eclipse project to Gradle (via Configure -> Add Gradle nature), I get the following exception:

org.gradle.tooling.BuildException: Could not fetch model of type ‘EclipseProject’ using Gradle distribution ‘https://services.gradle.org/distributions/gradle-3.0-bin.zip’.

I’m running Buildship 1.0.18 and Gradle 3.0. I’ve tried both Eclipse 4.41 and 4.6.

Is there a step I’m missing?

EDIT:

More precisely, it seems to fail when running code that loads in a properties file in the project root directory. When I run gradle from the command line this problem does not occur. Is there a way to force Buildship to set the root folder?

Can you please attach the full stacktrace?