I'm using El Capitan, and I went to my Mac to check my calendar (which is sync'ed to iCloud). I needed to check the details of an appointment I had 3 years ago. I went back, opened that month, and I saw all my entries. And then after a second, they vanished.
Why did this happen, and how can I stop this from happening?
And, can I use Time Machine to retrieve my old Calendar entries?