RE: Teams Webinar Registration Link - Issues
If you create a Teams Webinar from your Teams Calendar, create your form etc and save it. When you take the "copy registration link" url and then go to the Marketing App and create a Ivitation Email and CJ to send it. When you add a URL button and paste the copy registration link text, it seems fine. It event works when you make a test send.
However, when it gets sent via a CL in the system, that URL links gets changed and nobody can register. I think thats what happened in your case?
Its actually a BUG which i reported at least 3 weeks ago and for which Microsoft made a quick patch on our system to fix it. The patch made that the copy registration url link doesnt get changed.
Then you recipients can simply register, on your Teams Reg Form, get a quick confirmed notification, followed by an Email with an add to calendar ics file included. Its actually much quicker to create Teams Webinar event this way, if you do not want to create Leads in your system.
You might need to create a support case with Microsoft.