new 'remind me' mailbox not showing in Mac Mac sidebar

I'm quite excited about the new remind me feature in Ventura. I have upgraded, and can set the follow-up although there is no 'remind me' mailbox showing in the sidebar?

How do I get this to show?

I have looked in the settings for mail, and the apple support page:

Use Remind Me to come back to emails later in Mail on Mac – Apple Support (UK)

I am also not seeing the notifications (although they are turned on in system settings)?