I have updated SU pro on my Mac to 18.0.16976 and when I check the Update button is says there is a new version and this is straight after I had updated??? I closed SU down and then restarted and if you go to Check for Update is still syas there is an update available??..What is the latest version number.
Latest is 18.1
It handles some Mojave issues , thus Mac only and since you are on 10.11, probably not for you!
Were did you download your version?