Add Registrant to Webinar call always giving 404

Hey all, been digging into the forum and found old versions of this question, but none of the steps in them have worked. We have a webinar we are trying to add registrants on, yet we keep getting a 404: Registration has not been enabled for this webinar.

I have turned on the Require Registration setting, we have the highest paid webinar plan, and I’ve manually changed the Approval type and tested each available version.

Any assistance would be very appreciated!