I drew a simple design with few capacitors just to learn how component links work in altium desginer. (Image 2, pic a)
I checked manualy one by one all capacitors and I saw that UIDs are matched with pcb document. (Image 1, pic a) In Project -> component links -> Perform Update, a message popup "component links are up to date" appeared.
I tried to change the designators of my schematic between two components. (Image 2 pic b) After I executed the changes on pcb document I checked again their UIDs manually. I saw again that the UIDs are still matched correctly. (Image 1 pic b)
However, when I hit again, Project -> Component Links... -> Perform Update, a message inform me that "Component links modified in... 2 Links modified" Which are those two links and how were they modified? The UIDs seemed to be matched even before I perform update.