How come sometimes the Primary column has to be positioned first in a report, and sometimes not?

Seatora

Why did Smartsheet allow me to move this primary column to a position other that 1st? Here's an example:

SteyJ

https://community.smartsheet.com/discussion/112923/how-come-sometimes-the-primary-column-has-to-be-positioned-first-in-a-report-and-sometimes-not

I believe this is usually caused by grouping. Once you start grouping data, it puts the primary at the front so it can store grouping data at the beginning of each header.