What tends to happen is that the males return first from hibernation. When they first return they feed up to put on some of the weight they’ve lost during hibernation. Males have larger ranges than females, so it isn’t surprising as time goes on that they visit the areas of their range, which might not be quite so good as far as the food is concerned, but there may be females around – that sort of thing. It may be that you are on the edge of some ranges. But also once the females have returned the males spend a lot of time on courtship circling, which means there’s less time for them to be visiting feeding areas. You don’t say, how many hogs were visiting, but if there were only a few, it’s more likely that one or more of these scenarios could be the cause.
Also if any of the hogs were last year’s hoglets, it’s quite likely that the young males will gradually move on to new ranges. But if they are moving away from the area you are in, others may eventually move into that area.
Then it may be that other people have now realised that there are hogs around again and have started feeding. Someone may have been doing some DIY in their garden and routes, may have been blocked and hogs may have to find a new route, etc.
Lots of possibilities. But, don’t give up. I would keep putting a bit of food out and definitely water all day every day. Those same hogs, or others may appear.