Why is part of the map information cut off?

This is a limitation caused by the FAA's publication of individual charts (vs. seamless charts).  We can't stitch these charts together perfectly, but we're working hard to make them look as good as possible.

Image 1:  Seam running north to south west of KBGR.  This is where two charts join imperfectly.

TIP: When you are unable to read information near the seam on the chart, tap & hold on the map for the popup of nearby Airports, Nav and Waypoints.  VOR frequencies are shown under Nav.  On an airport, tapping More > Details will take you to that airport page for frequencies and other information.  Also, try looking at a different map, such as an IFR low chart, for any missing data.

Image 2:  Tap and hold to view information.

Last, if you zoom near a seam of a TAC chart, it may initially look like a seam issue, but it is not.  You can identify this by the white TAC line across the seam area (See image 3).  In this case, simply zoom out so that the TAC is not showing.   

Image 3:  TAC and VFR charts displayed at the same time.  This is not a seam issue.