Since many people are running into this issue, and...

# intellij

[rocketraman]

Since many people are running into this issue, and it appears the only fix is a manual plugin download and install, I'll put the download link here for others:
https://plugins.jetbrains.com/plugin/6954-kotlin (use the 1.1.3-release-IJ2017.2-2 download, or the appropriate EAP)