Not all attached images are displaying – old Expositio theme

Hi, I’ve recently resurrected my website and I’m using an old version of Expositio theme.
The thing is, when I used it a couple of years ago, WordPress was of a different version, and maybe that’s the problem. The process of creating a new gallery is simple: you create a post, attach images but you’re NOT inserting them into post body, add categories, title, and voila! I’ve also been using Better Attachments plug-in for easy rearrangement and adding captions and titles.
Now I’m trying to create my website again, using the same theme, but I’ve encountered a problem:
I see that ALL needed images (say, 18 of them) are attached to the post (I can see that in Media Library). But only 10 of them are shown. I looked into the source code – yes, link to only 10 of them. Even though the rest are shown with an option of “Detach”, and I can see they’re attached to the post with Better Attachments plug-in or without it. And I can’t figure out what could be the problem. I’m using the same images as before, same theme..
The link to the post I’m talking about – you can see 10 images, from pm01.jpg to pm10.jpg, but nothing past that. Even though I’ve attached all up to pm18.jpg…
I’m going crazy, help!