Calendar Breaks Menu

I have a page that contains a calendar and calendar list. On that page the sub-menus disappear which renders parts of the menu useless. The calendar page is the only page on the site that is affected.

Calendar page: https://www.parkervillechurch.org/calendar/ (Affected)
Homepage: https://www.parkervillechurch.org/ (Unaffected)

The page I need help with: [log in to see the link]