Debug breakpoints in value classes not working?

I've been struggling with some specs2 tests, in which the Intellij debugger has been refusing to stop. The relevant breakpoints being skipped were in implicit wrapper classes, defined using Scala 2.10's value class feature. Since the Scala compiler heavily transform value class code, I wondered if this might explain why the breakpoints were not working.

I tested this by moving the breakpoint into a submethod, factored out of the value class, and sure enough, the breakpoint worked OK. So I think there might be a debugger bug here...

-Ben