Time dont run 4 few perner when run for entire population with a new schema

Hi!

I have been observing that in my client's system Time don't run for few employee when run for entire population even after using forced recalculation for all employee though Time runs properly when run for those missed employee individually.

Just to add, we have used 3 different schema in last 3 months as the old schema is going through lot of changes and I was asked to release the changes in slots hence I ended up creating 3-4 schema (using 1 schema at a time of course).

Please suggest what could be reason for that.

Regards

Sunita