Form 2.0. Webinar registration for known leads with form bypass

I’m using a Form 2.0 for a webinar registration where known leads bypass the form and are shown custom html with the basic Form 2.0 tokens (Welcome back “names”, default button, and not you? token). Unknown leads are shown the form.
I can get unknown leads registered from the form, but not the known leads with the form bypass. I’ve tried a couple Trigger campaigns, like “Clicks on Web Page” with Link Name contains (url of Thank You Page) but that’s not pushing them through to GoToWebinar. Flow step is Change Program Status to Registered and send the confirmation email. What am I missing?

Thanks