In version 2018, by default, the Pan and Zoom tool will add keyframes for each face it detects in a still frame. These keyframes include a one-second pause on each face. Additionally, the program will extend the duration of the still photo on your timeline by 5 seconds for each face it detects.
This is often not the Pan and Zoom effect users prefer.
To override this auto-featur, click the Settings button in the lower left of the Pan & Zoom workspace. Change Hold Time to zero. Click OK to save these settings, then click the Reset button in Pan & Zoom workspace.
From this point on, when you add a still photo to your timeline and then open this clip in the Pan & Zoom Tool, there will be no face frames automatically added nor will the length of the still be extended beyond its default 5 seconds on your timeline.