Ensemble with matching geometry: summation from polygon give unexpected infs

[kriben]

Steps to reproduce:

1. Import ensemble with matching geometry
2. Create a polygon filter in 3d view
3. Create grid calculation.
4. Set this expression: sumVol : = sum(cellVol)
5. Use SFIPOIL as cellVol.
6. Use filter by view (view with polygon filter).
7. Set "Non-visible cell value" to "User-defined", and default value to 0.0.
8. Set "Apply to additional cases" to "All cases".
9. Click calculate.

Expected result:

• Should give same value as "Sum" in histogram, and no "inf" values for any of the realizations.
• Inf values

Actual result:

• Occasionally inf values for some of the cases (should not happen since undefined values are set to 0.0).
• The sum in the histogram differs from the computed sum.

See image below: