Not sure what a missing button means? You log and see "no buttons"?
Run autoconfig-buttons-freepbx.sh script, inspect the output. Does it appear to be complete? If so, then your problem might be related to the user/group configurations and having groups assigned to users. Edit one user, be sure it has no groups assigned(checked), and try to login again.
Unfortunately I cannot give you a more detailed answer as your problem details are a little bit scarse.
