Calendar Month view doesn't display all entries.

Steps:

1. Create some items and schedule them to be published later.
2. With an empty publishing queue, schedule the items to be published in 6, 7 and 8 days from now.
3. Go to Content / Calendar.
4. Check the Month view.

Actual: Only one of the items is visible in Month view.
Expected: All scheduled items are visible in all views.

Remarks: Week and Day views work fine. It can be tricky to reproduce. It seems there's some issue with the range but it's difficult to pinpoint. Also it could be something to do with the end of the month (because an item scheduled for the beginning of April is visible in Month view for April).