This still is a problem for us. I am entering a number of all day events...camps, holidays that sort of thing, and it continues to show up as 2 days. For example, I enter 'New Years Day' on Jan 1 as all day event and it comes up showing from 1st - 2nd Jan (2 days). Im in Australia, using Mac OS, Safari. I have also tried it on Mozilla, with the same results. It's getting frustrating as camp dates appear to start a day earlier and finish a day later than is the case.
I did not find the right solution from the internet.