I have the following problem on IntelliJ IDEA 14:
I created a Play (Scala) project using the Activator (v1.2.10). Then, I converted it to an IDEA project using act
act
Have you tried File | Import Project and select build.sbt file?
File | Import Project
build.sbt
IDEA imports it as an SBT project, with all the dependencies properly resolved. It works fine for me on IDEA 14 and on 13.
SBT