Hidden events are incorrectly labeled

[bruceharrison1984]

Describe the bug
Sometimes hidden events are not correctly flagged as not visible, even though they are clearly hidden from the UI

To Reproduce

• Add an onMoreEvents click handler to print all events on that day
• Overflow a date by adding additional events
• Observe events are hidden
• Observe console output labels all events as visible

Expected behavior
Events should be labeled as not visible if they are hidden