I try to add hours and minutes to start publishing date and creation date like that:

2018-07-23 21:45:00

But when I save it just erase the hours and remain only the date: 2018-07-23

Any way to add hours and minutes?

I even don't have the clock in the calendar menu..
And in articles it always show 00:00..
When I type the exact hour manually it just erase it

Normal joomla articles clock works good only with k2 is the problem
I am using joomla 3.8.7
K2 version is 2.6.8

If I upgrade to K2 version 2.8.0 will I loose any K2 articles,categories,tags etc..??

Hello,

K2 2.6.8 is several versions behind.
Please backup and update K2. This is the calendar in the latest version jmp.sh/NQjYnPj