Hi there @ThomasOos, 

Welcome to the Community! Thanks for sharing your issue with us, happy to help! 

I have a couple of questions that might shed some light here what might be going on here. First, when you say that other times this form doesn’t work and that you’ve tried different emails, does this mean that you’ve been testing and filling out the form multiple times yourself? Instead of other peers or colleagues trying as well? If so, it could be possible that our List Bombing prevention feature is kicking in here and stopping subscribers from being entered into your list. In order to protect the integrity of our customers’s  lists, Klaviyo has created a feature that will prevent subscription from happening if we detect too many "tests" from one IP.

If you sense that your page is having a lot more errors than it seemingly should, I’d encourage you to re-investigate how the page was set up to ensure that there are no errors that could contribute to it not functioning properly. In my experience, many clickfunnel page errors, such as an issue with form submission, can be attributed to an error in page setup.

Finally, there are many things to consider. if you’re noticing this time delay of the first flow message being sent out. First, since you mentioned your lists are set to double opt- in,  the delay could exist because users are not immediately confirming their subscription again after the original form submission. Double opt-in lists will not sent any messages connected to list-related actions, or any messages in general, until this is confirmed. Additionally, sometimes the time it takes to deliver a message is also up to the inbox provider itself. The delay might be related not to an error, but the inbox’s discretion of when they allow their client’s emails to be received.

Hope this helps!

-Taylor