I get NoClassDefFoundError when compiling my Scala application through sbt-console until I also do a "Refresh project" on my build file. Why?

I've been first told by colleagues and finally I've now it confirmed myself: running the sbt-console on Intellij may not be enough to get the Scala application effectively running -- one has to be careful to also click the "Refresh project" if wants to be sure that at run-time no `NoClassDefFoundError`s are found.

I always assumed that the "Refresh project" option would only serve to get syntax highlighting and IDE related features, that is, that as long as I ran sbt-console or sbt in the command-line, no actual harm would be caused to my generated Scala code.

Why is this so? Am I missing something?

Jorge