I can't be sure if this is exactly an Android 5.0 related problem, but it's never happened to me under Kitkat or Jellybean using the same devices. I create an event either by speaking into Google Now and saying for example "set appointment for July 1 at 11:00am dental" or by manually entering the info in the calendar app. The problem is that after confirming and saving the event it doesn't show up on either the Google Calender widget I have on my home screen or the Google Calendar app. This is happening on both my Nexus 4 phone and Nexus 10 tablet. Google Calendar is up to date. The strange part is that if I sign into Google on my PC and open the calendar page the event is there on the date for which I created it and also I'm getting notifications via Gmail prior to the event so I know the event has been created.