Mark, thanks for your comments.
I have been using Effect Leverage. What puzzled me is that the analyses have been run against 4 different "By" groups. On one data set all 4 groups were as expected, on another 2 of the 4 were missing leverage plots and on a third just 1 of the 4 was missing leverage plots.
These results were also repeatable.
Anyway, whatever the reason, I can check the leverage plot options from the Row Diagnostics dropdown menu as you suggested. So problem solved. (This was usinh JMP14, by the way).
Thanks again, Roger