watchCSS on Safari OSX Flickity does not activate within hidden container

It would seem that Safari does not render :after elements within hidden containers, when using watchCSS in Flickity within a hidden container, the create process skips activate. Then when calling resize() upon wanting to reveal the container the Flickity has not properly activated.

https://codepen.io/johnhornsby/pen/NgEQKg

Start by reproducing the Safari OSX case in the linked CodePen, focusing on Flickity's watchCSS behavior inside a hidden container. Trace the create process and the resize() call to determine why activation is skipped; done means a Flickity instance in a previously hidden container activates correctly when revealed and resized.

Written by the indexing model from the issue text.