The time of the event is saved properly, when I create an event. But when I click on the edit, the time of the event is displayed wrongly. It is very easy to save it back wrongly, if you don't recognize it (for example when you want to upload an image, but don't double check the time which was already properly set earlier).
Just to be sure I tested it in IE as well, but as I expected the issue is not browser-dependent.
--------------------------------
Your browser/os information:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:52.0) Gecko/20100101 Firefox/52.0 (this will help us make sense of your bug report)