Dropdown menu not displaying Wordpress

Question

A customer has just complained that they're unable to select sizes of a product. Upon looking the drop down menu isn't working.

https://targwall.co.uk/product/dark-concrete-pvc-wall-panel/

It's happening in the backend too when I go to click the dropdown to change the heading too!

I've checked and there is no CSS blocking this.

Not sure what's happening here!

Answer 1

This is a CSS issue not related to WordPress maybe to Woocommerce, try adding:

.select2-container{ z-index:10000; }

the number seems high but i tried different ones thats the one that works.