Variation swatches not crossed out on stock status

Hi,

There’s an issue with the variation swatches on our site. If a variation is out of stock it should display
a cross / blurred out selection like this: https://share.getcloudapp.com/z8uGvOk5
But it shows everything in stock: https://share.getcloudapp.com/04u6e2PG
As you can see in the screencast, the before class is there but does not work properly.

I’ve deactivated all plugins except Elementor, Woodmart core and Woocommerce and all custom css but the problem remains.