Hi guys,
I write an article and set the "Created by" article author. Save it. All is OK.
Now, I need to change the article author, so:

• I edit the article
• select the "Created by" filed
• the pop-up window search is opened
• search and look for a new user
• select on a new user
• but when I click on the new user the pop-up window is closed and nothing happen.

I have to repeat that a second time and the user is finally changed and I can save it.
Be careful, the last user search is always prefilled, so in the case I need the same new user for another article, when I select the "Created by" filed the new user into the pop-up window is prefilled. In this case the window is closed and the user is changed correctly.

System information (as much as possible)

last joomla 3.6.5 and PHP 5.6.x

Additional comments

Community confirmed the Bug here: https://forum.joomla.org/viewtopic.php?f=728&t=944655&p=3462518#