I recently got a Samsung J3 with Android version 5.1.1.
When using it I noticed that the Call log was quite useless. I had seen others report the same issue on forums with others trying to leave help merely stated that it is very easy to Create a New Contact from the Log.
It appears that there is a small bug which makes the Log File useless. I will discuss how to work around this. Tap phone:
If you click on the Log the last missed call or called number should be displayed. If you tap this unsaved contact you should be able to create a new contact from that number then and there or call the contact:
You should get the following screen:
The following screen should alternatively display if you press and hold the contact in order to give you the options to clean-up the log. In my case this showed every time I tapped this screen making the log quite useless:
To get out of this press [←] and then press the manual dialer:
Select Log once again:
Press [←] to exit the manual dialer. You should now be able to tap the contact:
You should then get the normal screen with the option to Create a New Contact from that number or directly call/text respectively:
Type in the name for the contact and then select Save: