Access to Channel Calendar Event Chat

I've created a Private Teams site and set up a Channel Calendar on the General Channel. I've invited both Channel Members and Non-Members to meetings set up on the Channel Calendar. I'm having a couple of issues relating to accessing the meeting chats:

1. The Meeting Chat for events created on the Channel Calendar do not appear in anyones chat history
2. Attendees who are not members of the Teams Channel are unable to view or participate in the chat during the meeting or access it after the event.

Do all attendees need to be a member of the Teams Channel or the Teams site to access the chat? and is the only way to view the chat history via the meeting post in the Post Tab on the Channel?

I've checked the Meeting options and all the engagement is unlocked so in theory all users should be able to access the chat.

Thanks