I've the same problem. One "solution" (or workaround^^) is to use always the full qualified names of all classes. It is also annoying, but it works fine. At least until the Problem of the lost imports is gone.
Yes, this is the only workaround we have for now. I haven't found another one.
the problem is probably easy to fix for plugin developpers. So let's wait for the next release.
This issue was resolved with the latest release of eclipse plugin.