Hey man, I'm having a very similar problem from the WordPress Anthology book (#1).
I can't get the drop-down menu item(s) to select from the 'Add new session' page. Well, you can select the item(s), but upon Updating the page, the selection is cleared to default.
And the speaker & session pages aren't displaying correctly for me, either.
I've spent a good bit looking around here, but can't find any other threads on the topic.
Btw, g, are you unable to see to Speaker & Session options in the sidebar menu? That what you are saying? OR, you can see those, and cannot see the actual fields on the 'Add new' page?
If the first option: try adjusting your " 'menu_position'=> " values in site-custom-types.php to 30 & 31 (speakers & sessions). I had to do that to view them in the sidebar.
Hope that helps.
AND, any new (mo' betta') help is greatly appreciated!! Thanks, in advance.