overflow-y not working in safari inside a modal

I don't have any IOS product to verify this, but it seems like overflow: auto is a known Safari bug.

Try this:

#filterOptionsContainer {
  overflow-y: scroll;
  -webkit-overflow-scrolling: touch;
}

Try applying this inline , or through a Jquery Script

 style="overflow-y: scroll; -webkit-overflow-scrolling: touch;"

or through a Jquery Script

$("#filterOptionsContainer").css({
    "overflow-y": "scroll",
    "-webkit-overflow-scrolling": "touch"
});

You can try this. It's working fine with Safari.

#filterOptionsContainer {
  overflow-y: scroll;
  -webkit-overflow-scrolling: touch;
}