What updates last modified date

There is no possibility for that field not to be updated if you edited the record itself.  Note that this field will not be updated if its parent records are updated or child records are updated.

If you can actually prove that, you would need to put in a support ticket because that seem very impossible to me.

Hi Shelby,

I would agree with Mark that Lost Modified Date should be driven by any record change driven on that record by updating or changing its field values. The one thing that doesn't change this is any summary or look up fields that change when the parent or child records change or any formulas that change based on those summary and look up fields. If a user Grid Edits a record directly and changes the values to be different from their original values and those changes save the Last Modified Date should also update and capture that. If you are seeing a pattern of that not happening I would definitely suggest opening a support case to let the Care team know the specific details so they can look into it as that would be very out of character for that field. 

Thanks, this is working I was just expecting the wrong thing.  Appreciated!