Hello, I'm new here. Anyway, I've been browsing around and noticing that some of the thumbnails on pages are simply blank/missing. Is that something to do with the site or something I have to deal with?

I think you're just seeing pictures that are "Hidden", you can click a button right below the search box to show the hidden thumbnails. Most of the time they're hidden because of yaoi, futanari, toddlercon, or something extreme like gore, etc.

If you see text and no thumbnail then that image is missing. It's due to a bug that is very random at appearing.

I've noticed that occasionally, if you wait for a few moments, the missing thumbnails will show up. Not always, but often enough. Refreshing the page helps as well.