I've been observing what appears to be race conditions between the idea and play compiler. I'm using version 2.0.x of play and running in the "~ run" mode. Quite often I'm seeing things get out of sync. Sometimes it will manifest itself in no class def found errors and other times it will manifest itself with the execution of older versions of classes. The latter is the most frustrating because you lose cycles trying to figure out if your code is wrong or the compiler just didn't pick up the change.
I didn't experience this in 12.0.x. Anyone have any suggestions on how to resolve this?