Hello,
as for the topic title, unfortunately it’s not possible to disable the buttons on some pages.
As for the actual issue, it’s a well-known problem with some themes adding their own buttons. It is easy to hide them (yes, they are hidden at the moment), but much harder to disable. Therefore clicking on the buttons from Qty Increment Buttons triggers both the event from my plugin and the event from the theme. If this happens only on this product page then it is possible that for some reason the theme adds the buttons just to this specific product type.
For some of the most popular themes, I resolved the problem individually, but in the plugin version that I’ve just released, I also prepared a generic version to stop many themes from adding these buttons, that’s what patch notes say about it, please let me know if this solved the problem, if not I’ll check what can be done with this specific theme:
Added "buttons_added" class to div.quantity in quantity-input.php template. This will stop some themes from adding their own buttons.
Best regards,
Ryszard