Oh my god! You just saved me!
It is true, I can confirm, importing through camera roll is the perfect way to end up with a complete mess! Importing from files: everything works perfectly!

I would offer you a beer, but:

1. I don’t know where you live and I don’t want to be sue for stalking 😂
2. with all the social distancing measures around the globe we will just end up arrested or with a huge fine in the best case scenario

So for now just accept my infinite gratitude. I can get back to work on my little project now 😊

This is what I mean

Re: Animations are broken.

I’m having exactly the same problem.
I created the images with multiple softwares, always saving them as .png.
In the camera roll I can see they are png because clicking on them will show the black background. Also exporting them and opening them on a Mac confirmed they ARE .png.

When I try to create an animation here, following the manual instruction step by step, I face the same problem reported by the OP.
The software just import the first image, ignoring all the other.
If the animation is made with 4 frames hyperPad just import the first one (correctly) and then clones it 3 times, for a total of 4 images. The first one is the actual first frame, but the other 3 images are not the one I selected but clones of the first one displaying only the top half!