Hi ??
Well, I’ve found the same behavior you describe in my development environment (Vagrant), but not in production sites. Definitely annoying :-\
Trying to debug right now.
It seems there is a problem with some empty value into the javascript code related to datepicker. I’m cleaning up the needed javascript load in the WordPress admin side as much as I can, but it isn’t resolved yet. And I really don’t know why is working fine in my production site while it doesn’t in development.
The datepicker jquery-plugin is loaded by WordPress by default, but no the timepicker one.
My experience with jquery/javascript is limited. This is the error I get, in case you have more experience than me, or somebody can help:
Uncaught TypeError: Cannot read property 'length' of null
a.extend.formatDate @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-datepicker&ve…:31
a.extend._formatDate @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-datepicker&ve…:32
a.extend._selectDay @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-datepicker&ve…:31
b.selectDay @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-datepicker&ve…:31
m.event.dispatch @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-datepicker&ve…:4
r.handle @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-datepicker&ve…:4