Rules marked as "custom", won't revert using features

I'm having an issue with Rules + Features.

Following a change to some rules in dev, I've exported a new version of the feature and updated our test environment.

When I try to revert the feature to install the new rules, however, the updates don't take and the feature remains "overridden".

The rules themselves are also all listed as "Custom", regardless of whether or not they were changed in the latest feature update.

The only way to update each rule, is to "delete" them individually, at which point they revert to the latest version in code.

Any thoughts?

Thanks!