I suggest that you submit this to the JMP support group. You may be more comfortable providing them your data. I have never run across this issue, and having the data is really necessary to investigate the issue.
I'll agree with @txnelson. It's going to be hard to diagnose without seeing the data table directly. I've never seen a case where JMP is plotting the data incorrectly. If you can share just that column of data or even just those two points as a JMP data table that will help.
What does the Distribution report for that column look like? Can you share that?