Kia Ora Lyn

I tried adding a seminar in the past and adding attendees and this worked Ok, I was using version 12

Are there any messages that show why the learner is not able to be added such as conflicting times with another seminar.

There are a few settings around the signup workflow in Version 12 . Setting the 'How many times the user can sign-up' to more than one may help if this is the reason the user is able to be signed up.

If this doesn't help can you or your Partner create a ticket in the Support desk and add details on the Totara version and Seminar settings so we can see what the problem is.

Regards