You can experience this in the sample at: Intro to graphics - 4.5
If you pan the map so that one or more of the on-screen graphics are completely outside of the view and release, then click and drag the map so the graphics would come back into view they do not appear UNTIL you release your mouse.
Is there any way to custom refresh the graphic layer(s) while dragging so that the icons are updated and appear at all times?
Tested on 4.x and 3.x and experience the same issue in all samples and my own tests. The app I'm working on involves the need to quickly scope out where different markers are while walking, which is much easier if they can drag the map around while in motion and the marker icons will appear as soon as they are on the screen, rather than only when they release their finger.