Inside a position: fixed; element, scrolling elements will "lock" if you try to scroll them the wrong way at the start of a touch.
Example: touch the screen and drag downwards, then back up. The element won't scroll. If you release, wait a few seconds, then try dragging upwards, it will scroll.
http://12me21.github.io/scroll-test.html
body {
   position: fixed;
   top: 0;
   bottom: 0;
   left: 0;
   right: 0;
}
#scroll-container {
   overflow-y: scroll;
   height: 100%;
}
#scroller {
   height: 200vh;
   font-size: 50px;
}
<body>
   <div id=scroll-container>
      <div id=scroller>Test<br>more text</div>
   </div>
</body>
This answer: https://stackoverflow.com/a/51733026/6232794 seems to be the same problem I'm having, but the fix no longer works. It seems to happen inside all fixed elements and isn't caused by -webkit-overflow-scrolling: touch; anymore.
Is there any way to fix this now? Or do I just need to avoid position: fixed; entirely?