This is a safety feature. Office chair casters are equipped with a load-dependent brake. This means they lock if there is no load that stops the office chair from rolling away uncontrolled when standing up. When loading again, thus when you sit back down, the brake releases and the casters can run free.
When using your casters, have you taken the rule from point 1) into consideration? Hard floor = soft casters, soft floor = hard casters.
The marks on your floor probably depend on the quality of the tread material of the casters. Gross Stabil twin wheel casters are coated with high-quality plastic. This is decisive for the abrasion condition of the casters, marks on the floor will therefore be avoided.