Sources can't be located via sbt-ctags or sbt-sublime

[coltfred]

It appears the sources for atto cannot be located by either sbt-ctags or sbt-sublime.

I'm running SBT 0.13.5 and trying to get atto 0.3 on scala 2.11.

Both of these utilities find org.spire-math.spire, but for some reason they can't find the sources for atto.