This is a known bug. Thanks Shane Kumpf to pointing out a fix to get InteliJ Maven Repo working with autocomplete
This is a bug in Intellij 14.1 (and many earlier versions).
See IDEA-102693 which includes a zip with the fixed maven plugin jars. Replace your intellij jars with those from the zip file.
If that doesn't work, take a look at your idea.log (sudo find / -name idea.log to locate it) for any exceptions and research those and/or post your stack trace here.
--NO_CROSS_POST