It sounds like it could be something going on with your database. But you haven't given any versions for anything. What version of Bacula? What database and version? What OS? Etc. Statistics for your backups? Volume, number of items, etc. Other configuration options.
If you think it might be a bug, then you should post it to the Bacuala users list and see what they say. However, I think it's more likely that something has hung with your database.