Overview
Campaigns run in cycles of 3 hours and never at the same time to mimic human behavior and protect your LinkedIn account. So if a campaign is not running, it doesn't mean it's stopped.
If you have multiple campaigns, one will run and the rest will remain Active (on Pause with a green circle) and they will take turns to run automatically one after the other.
This means that the campaign will not always be running, but it can be active waiting for the next run. Please take a look at this article that explains campaign status.