Bootstrap modal Iframe in iOS 12 hidden behind content
The solution to this ended up being that we needed to force hardware acceleration by including the following css in the <head></head> of the child document (element within the iframe (frameable.html in our case)):
<style>
body{
transform: translate3d(0,0,0);
}
</style>
I however cannot explain why this resolves the issue, or why it's required for ios12 as opposed to ios11. If anyone else can shed some light onto that topic, I'm sure it would help someone else down the road.