Why does my calendar go to Jan 1970 when I try to select a day in April 2016?

[AC Question]

This is the only Month it happens in. A co-worker has the same issue with his S6.

 

[Rukbat]

January 1, 1970, at midnight, is Unix time 0. Something in the calendar app is setting the date to 0. Try installing a different calendar app to see if it's the calendar app or the call to Android for the date that's causing the issue.