Is there any news on this issue? I'm experiencing the same problem. When I contacted support via chat, they said my problem is caused by page sizes that are too large. While it's true my pages exceed the recommended sizes, that's not what is causing the problem. I can scroll galleries fine on my older ipad (ios 10.xx), desktop, and iPhone, but they are frozen on my iPad Pro running ios 13.3.
What are any of you doing to address it? Is there another template that looks similar but works better?