Campaign URL's in Goal Funnels?


I have been using Matomo for the first time, and I have a question regarding Campaign URL’s and Goal tracking.

It is regarding a ecommerce website. We have created several Campaign URL’s for banners on External websites. The goal here is to track incoming clicks from these websites through the banners.

This works (as far as I can tell). In the Acquisition section we can see the Campaigns listed.

Now we also wanted to try and see how many people that come onto our website through these clicks actually register as a customer. So we created a new goal, with a funnel.

As entry page, we listed the exact campaign URL with UTM parameters. The second step would the next page which is a register page. Then after registering, sadly there is no thank you URL. User are directed to the /account page. So that is the last page in our created goal.

But I have noticed that visitors who did not come to us through the Campaign URL, but do go through the funnel steps, also trigger this goal. So it seems the UTM parameters are not a valid way of selecting an entry URL?

How can I track the registrations of users that entered the website through a campaign URL?

Thanks in advance!