The bounce processing function is very processor and resource intensive. To maintain optimal system user response and performance, bounces are processed every four hours in batches, instead of real time. If you sent a campaign and the Statistics are reporting '0 hard/soft bounces', then the bounce processing has most likely not run yet. Simply re-check the Statistics again in a few hours.
If in the unlikely event you sent a campaign and expected some bounces and none are reported after 8 hours, please send a note to email@example.com or register a support ticket and this will be investigated immediately.