I also just came for reporting a problem with a call hierarchy.
Using Scala-IDE 4.6.1.v-2_12_201706090854-f511faf (yesterday installed in a fresh Eclipse Oxygen), I observed (with an existing Scala project) also that the call hierarchy is often incomplete (just showing calls in a test, but not in production code, for example).
But it is not as simple as "same file" or "different files" (my tests, which are found, are generally in different files).
My first idea was that implicit parameters were causing this (as the tests (or rather Mockito mockings) always pass them explicitly, while the production code has them implicit), but in one case a productive call is actually found (and not passing the implicit parameter explicitly).
In some cases it seems to be more like "If it is in the same package or a package higher up in the hierarchy, it is found, otherwise not."
E.g. a call from controller package to a service in the service package is not found, but a call from service.xyz.XYZService to service.xyz.abc.AbcService seems to be found.
In other cases calls from a different package are still found, though.
I'll try to find some examples with public scala code instead of my proprietary project.
Paul
PS:
Trying to join an existing organization?
Ask your account owner to add you in Assembla.
(If I continue with creating an account, I'll have to choose an domain name, i.e. I get a full new organization. I don't want that.)
That might be the reason that you got no new bug tickets for some weeks ;-)