Blank Edit page for Calendar View after D6 to D7 upgrade

I am currently testing an upgrade of our websites from D6 to D7. A few of these sites use the calendar module to display events. After upgrading to D7 I am unable to edit the Calendar view. The edit page is blank and only gives the option to "Update Preview". See screenshot attached. What would cause this?

Also, is there an upgrade path for the calendar module from D6 to D7 or do I have to manually recreate my calendars for all my sites?