product dependencies box not apperaing

Hello there, just having a go with your plugin, should be perfect for what I want. But when i’m in the backend and I go to change dependencies the box is really small and I can’t put anything in it. I tried changing the CSS but to no avail, the box gets bigger but I still can’t put anything in it.

Any ideas why this might be?

Cheers for any help.

https://www.ads-software.com/plugins/woocommerce-product-dependencies/