Products change to 'Sold out' as soon as a different variant is selected

Can anyone help? All my products look as though they are available, but as soon as an alternative variant is selected (in this case, Size: A3, A4 or A5), every variant shows as Sold Out.

Shopify help have said they cannot help because I have amended the code. The only code I have amended is removing code so that ‘usually ships within 24 hours’ is not displayed.

I don’t think it is an issue with Locations - I have only 1 location. I’ve tried having everything in stock, turning most product to ‘not tracked’, and also selecting ‘continue selling when out of stock’. None of this makes any difference.

I am not sure if I am able to reply to comments. Just in case, my url is www.robyncaleyillustration.com, and an example product page where this issue occurs is Bedford Blues rugby club, Bedford | PRINT – Robyn Caley Illustration

Any suggestions would be extremely gratefully received, my website cannot launch without fixing this.

Thank you!

@Robyn_17 could you provide us a link / URL to one of the products where this is happening?

Thank you, I can: Bedford Blues rugby club, Bedford | PRINT – Robyn Caley Illustration

Let me know if you have any issues - my shop is currently password protected.

Hello Robyn @Robyn_17 i think it would be a good idea to share your store URL link so the issue with regards to the products can be properly checked and assessed.

Hi @Finer , thank you, here is an example: Bedford Blues rugby club, Bedford | PRINT – Robyn Caley Illustration

Let me know if you have any issues with it - my store is still password protected.

Hi @Bundler-Manuel , it is Robyn Caley Illustration. An example product in which the issue occurs is Bedford Blues rugby club, Bedford | PRINT – Robyn Caley Illustration

Let me know if you have any issues seeing these pages, my store is still password protected.