Let's say you have a window open, and you want to navigate to a layout with a web viewer. You freeze that window, do some background stuff (record mods, whatever), then go to the web layout. Most of the time, all animations in that web viewer will be disabled in Safari. This includes transitions, animations using jquery plugins (like .confirm), and animated GIFs.
The workaround, if you have frozen your window, is to unfreeze it first by doing Pause/Resume (0 secs), then go to the layout. This allows it to load properly. You will, however, see the window's previous layout before it loads the new one.
This workaround cannot be done with the window off-screen either - the layout change with an unfrozen window must happen while it's visible.
Anybody else experience this? We're using FileMaker 16, but it happened with 15 as well. El Capitan and High Sierra.