I upgraded a test environment to v4.0.2 yesterday and the Fusion Charts on my tab are not displaying and say it is unsupported.
Fusion charts are working fine in 4.0.2 for us. Can please check any errors are there in browser console?
Seems "Chart type not supported" error message displaying from Fustioncharts. Could you please tell what style you are using?.
What was your old Rollbase version?