1) Well done posting your Vicidial Version with Build and even including your Agent Version.
2) Please include the full Installer version (8 is just the major), it should be 8.X.X with two more significant numbers there. It helps. Usually available in your splash/welcome screen when you log in to the Linux CLI. Also, of course, in the name of the disk .iso itself if you still have it.
3) Try creating a new user and a new campaign to see if you may have just overlooked something. Also be sure your Admin user is level 9, in the user group "ADMIN", and you've NOT modified any settings in the user group ADMIN. Anyone whose user group you want to edit should be in another user group, NOT admin. Reverting to the original admin and 6666 entries is often required for newbies.
4) When setting permissions for a user, remember that most BUT NOT ALL should be set to "1" to GET permission. Sometimes setting to "1" REMOVES a permission instead.
5) Ordinarily, an agent should never be altering the dial code anyway unless they are adding a new "manual dial" lead, and when they do this they will be adding the lead in the Manual Dial pane which has a completely different dial code field. I am now forced to ask WHY your agents need to edit this field? The only scenario where Dial Code would need to be modified would be when a client give an agent an entirely new phone number in a different country to call instead of the one at which you called them (a different country than where you called them is ... unusual).
6) This is not a general discussion. It's a support request. Moving to the Support board.