Just experienced this issue. When closing files on sevrer via FM Admin tool, the files says "closing" and nothing happens. I have waited up to 15 minutes and no change. The only remedy I found was to re-open Db files locally on PC, log in and log out which closed the files on server Admin. Experienced similar issue when opening files on server. Status will get stuck in "opening" mode.
Restarting server helps but this is not a good solution. Did anyone else experience this issue with FileMaker Server 11 or Advance 11?