Search for Class references suddenly stop working

I think I reported something similar at the last Release and now it has happens again.

I have a class `RemoteAgentManager` and i search for reference in my workspace but only some hits. Searching for `RemoteAgentManager` in `*.java` files reveals a lot more places!

Open one of this places previously not found *sometimes* makes that a refresh now shows this place, but missing other.

If I remember correctly last time it worked to clear some cache, but as this now happens again after upgrading to a new release I think it was not a one-time problem.

Sadly I have no clue how to reproduce this :-\