Not working for me

Hi,

I’ve activated this plugin and entered custom stock messages, but they are not working on my site.

Any ideas why? Maybe it’s specific to my theme ( https://flatsome.uxthemes.com/) / or my child theme

My site is here. https://www.isleofwightstudioglass.co.uk/product-category/crizzle/

Please note I am currently hiding Out of stock message by css, but you can see that new message is not showing when you Inspect Element in browser.

Any suggestions would be much appreciated.
Thanks

PS, should the message show on the simple product and the product archive?

https://www.ads-software.com/plugins/stock-message/