SBT integration appears to be failing in the latest community build (143.1821) and scala plugin (2.10)

Have created a SBT project with auto import.

The SBT file is as follows:

name := "unittest"

version := "1.0"

scalaVersion := "2.11.7"

libraryDependencies += "org.scala-lang.modules" % "scala-xml_2.11" % "1.0.4"
libraryDependencies += "org.scalatest" % "scalatest_2.11" % "2.2.6"

I then attempt to create a simple test as follows:

/**
  * Created by piero on 20/01/16.
  */

import org.scalatest._

class Sometest extends FlatSpec {


}

But intellij says it cannot find FlatSpec or scalatest.

Note this builds under sbt from the command line.

Does anyone have a workaround?99