Expected Finish & Free Float in Primavera P6

A sizeable number of Planners/Schedulers use “Expected Finish” feature in Primavera P6 to calculate the remaining duration of in-progress activities, especially for long-lead procurement items.

But did you know that this time-saving feature has an unexpected behaviour? For reasons I do not know, in-progress activities with “Expected Finish” applied have their free float reset to 0 (zero), as shown in the image and demonstrated in the video below.