Loading the metadata plist worked for me:

Turn off spotlight:
sudo mdutil -a -i off

Unload it:
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

Load It:
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

Turn on spotlight again:
sudo mdutil -a -i on

Now everything is being reindexed as expected.

For me it was not necessary to do unload/load procedure.

source: Link