Created attachment 394760 [details] Shows the column bug occurring with the minimum amount of css Noticed in Safari Version 13.1 (14609.1.20.111.8), verified still present in Mojave r259135 (See attachment or https://codepen.io/onlyforhisname/pen/LYVMLEV) When an item contains multiple columns using column-count or column-width and the first-level items have overflow hidden, any second-level children with position relative still take up space but are not visible (unless they are in the first column). May be related to https://bugs.webkit.org/show_bug.cgi?id=207991
As a temporary fix, I found that adding transform: translateX(0); to the main container will cause the items to show like normal
<rdar://problem/60991112>
Just adding that I also independently ran across this (Safari 13.1.1, macOS 10.15.5) with a replication here https://jsfiddle.net/dzucconi/fvxu4gc5/