missing some runs during monte carlo simulation

There are some runs that are missing during monte carlo simulation but if I re-run those specific runs, the results are there.
I am using  IC6.1.7-64b.500.15

Is there any setup that I missed?

This is an example.


this is another example.
In this example, I missed 19 runs.


This is the result after re-simulating only those missing runs.


This is my setting.