I am on PC not ps5, but there may be some similarities between how the two save games to offer where you might look. Go to load game menu. On PC saves go to a specific campaign. See if there is way to minimize/hide the saves from the most recent campaign you played. This would make it easier to see the list of the other campaigns saved games. If you did cross save between the campaigns this will be of no use, but I'm taking a shot that you actually did not and are just not seeing the separate saves of each campaign.