Since background jobs are initiated by the job scheduler supplied by the RDBMS, you need to ensure that the scheduler for your specific RDBMS is properly configured.
P6 Professional uses the SQL Agent service to automatically schedule background job execution for Microsoft SQL Server. Background jobs handles the maintenance of the utilities tables (for example, USESSION and REFRDEL). As part of background jobs, the agent runs the SYMON and DAMON stored procedures at specific intervals.