Some themes use special methods to display customized dropdowns and so on which involves hiding the default browser objects. The problem is that the CSS used is not specifically around the customized objects used, as such, our offer button/dropdowns may not show. The quick fix for this would be to add the following CSS:

If the Add to Cart button is missing:

.nudge-offer input.bttn, .nudge-offer button.bttn{ visibility: visible; display: inline; }

If the Variants/Dropdown is missing:

.nudge-offer form span.variants-wrapper select, .nudge-offer form span.quantity-wrapper select{ display: inherit; }

The CSS would be added here: (found at Offer Settings > Look and Feel)

Save and then refresh the page to confirm changes, you may need to refresh your cache.