Hi Elliot,
the meta_value in wp_postmeta was saved like this: 2015-11-10 20:00, so this is not a problem.
The problem was, that the default value of the new field date_time_picker is “16/06/2016 1:42 am” and not “2016-06-16 01:42:02”.
I changed this now with my fields which use the date_time_picker, but it was quite a hassle to update all my projects.
