CI 3.1.0 Email Lib producting empty attachments

I have the same.
The problem has already been reported, e.g. here:
http://forum.codeigniter.com/thread-6624...attachment

I see a lot of discussions about this subject. One user has modified the core email library, and was rather heavily criticised for that. Nevertheless, I've installed that fix also, because there is no 3.1.1 yet that fixes this.