Hi Zeno,
Thank you for your review. Have you checked whether the Snapclean is correctly attached to the cap? If it is not correctly attached, this could be the cause of the leak. Could you please check this? You can find a video here showing how to attach the Snapclean correctly in the cap: https://youtu.be/1wt-Zn-hC6g?si=gZK9--vkr-gqO0LA&t=18
If the problem is still not resolved, we will be happy to help you further via customer service. You can reach them by sending an email to customerservice@bibobrands.com.
Kind regards,
Team Kambukka