If you're encountering this issue, the likely reason is that one of more of the products in the bundle is out of stock. By default, if a product is out of stock, the bundle will still be displayed on your website but customers will not be able to claim the offer.
To avoid confusion, we advise that you enable the Stock Control option from General Settings. When Enabled, the claim button won't work if there is no stock for bundled products and we also display an "out of stock" label.
If however, in your Shopify Admin you have enabled the option to continue selling your products when out of stock, please make sure that you disable the Stock Control setting and your customers will be able to continue to claim bundles even if the available quantity of the product on your Shopify Admin reaches 0.