Hey @Sheena Milne51! Just to confirm, in the form's settings, do you have 'Auto-confirm new subscribers' unchecked? Like this:
If so, for the next step I would recommend reaching out to the team at SendOwl. They were the ones who created this integration with us, so they would be better equipped to answer questions about its functionality (and confirm if this is an expected behaviour or not, and if so, whether there is a workaround).
Of course, let us know if we can help with anything else from our end! :)