Email template tags not all working

I’m using the free version of the plugin, and when customising the emails on the email settings page, I’m finding only some of the template tags listed work in the emails that are sent out.

Some of them just show the placeholder itself in the email, for example %firstname%, and some such as %expiration% just show a blank space in the email.

I have checked that the member account has the details filled in on their profile.

Is there any reason some of these tags wouldn’t work in some of the emails?

Thanks.