Sorry, I make a mistake here. You can have job and file retentions less than volume retention. In this case, you will not be able to restore individual files/directories using the restore bconsole command / directory tree navigation. Maybe your problem is in your schedule and retention times configurations.
Bacula will not prune incremental jobs until next full. Maybe you need to adjust your retention times for jobs, files and volumes and also your schedule for full and incremental jobs.
Best regards,
Ana