Thanks a lot for your reply, Simon!
Indeed, the command was started, but the model was too big causing EA to crash. And since the model is so big, we were trying out a SQL database. Of course, we know that you`re not supposed to run Get (All) Latest with a DBMS, but only a single person was using the DB at that moment, and Get All Latest was called accidentially (but that shouldn`t be a problem, since no one else was using it). So we cannot start Get All Latest again because EA will just also crash again....
We also looked for the flags for this command in the DB tables, but we haven`t found a corresponding flag, yet. We now also found out, that some of the packages were still markes as ,,Checked out to" the user in the xml files in the VC repository (even though no check outs could be found via ClearCase), but removing this manually from the xml files also didn`t solve the problem.
But as I said, once I got a useful reply from the support, I will share the solution!