Bug on Delivers to Dropdown on header

Hi Folks

I currently have a developer in the UK who has been doing all my work but unfortunately he is busy at the moment to help us. Looking for a dev who really knows his stuff and can help us with this bug. We are using wordpress and a directory plugin called https://wpgeodirectory.com/

website is

shoppingonline.ie

On the header we have a filter called Delivers and this should be filtering shops by country. There is a bug where its showing shops that are not on selected on this country. The bug is not reproducible all the time. I don't know if its a caching issue, or what the issue is.

The sorting is current set to sort via package, and then by title, so i believe the results should not change each time the page is loaded.

At the moment it seems reproducible easier on incognito mode, but I have reproduced it on normal chrome mode.

We have lots of ongoing work so whoever is able to fix this will have more work in the future.

Many thanks

Scott