Welcome to the Forum!
It’s good to hear you have some hog activity there. It may be that the visiting hog is a male. They have larger ranges than the females, so it’s possible that he may be visiting other parts of his range on the days he’s missing. I have found that at least some of the males don’t visit every night.
But also, here, that it’s the females who are more regular in their visits, but it does vary a bit from hog to hog. I used to have one female visitor who you could almost set your clocks by! But even with females they can often be delayed from the actual feeding area if they are intercepted by a male and become involved in courtship circling.
Good luck with the camera. Hopefully it will give you a better idea of what is happening.
If you are interested in identifying the hogs naturally, I wrote a few notes a while back, which you might find useful https://www.hedgehogstreet.org/forums/topic/identifying-hedgehogs-from-their-natural-markings/
Happy hog watching!