Same issue for me. I am able to see changes in the job, however, they no longer link the way my old Jenkins used to.
Current config: Jenkins 2.65 / CVS plugin 2.13 / and ViewVC plugin 1.7
Old config: Jenkins 1.534 / CVS plugin 1.6 / and ViewVC plugin 1.6
The version of ViewVC I have is 1.1.26 on the CVS repository and it works on the old Jenkins server I have been keeping around for reference if needed.
Attached is an example picture of the OLD Jenkins showing the link in the changes of one of the jobs:
and also attached is a picture of NEW Jenkins showing the changes of one of the jobs with no link:
Both jobs have "Repository Browser" set to ViewVC as the selection in the drop down with the same URI.