I have discovered when using a clip region drawing a Datafield, the display is sometimes rendered incorrectly if the field is present on multiple positions of the screen. I have replicated the problem using the code example below on the simulator and on a physical Edge 830 device. The issue is observed on several of the screen layouts, here are examples for '3 Fields B' and '6 Fields B' - notice the incomplete rectangle on the center instance.

function onUpdate(dc) {
var w = dc.getWidth();
var h = dc.getHeight();
// Fill left half of field with black
dc.setColor(Graphics.COLOR_BLACK, Graphics.COLOR_RED);
dc.fillRectangle(0, 0, w/2, h);
// Draw full frame in black
dc.drawRectangle(w/4, h/4, w/2, h/2);
// Draw frame in white, but clipped to left half of field
dc.setColor(Graphics.COLOR_WHITE, Graphics.COLOR_RED);
dc.setClip(0,0,w/2, h);
dc.drawRectangle(w/4, h/4, w/2, h/2);
dc.clearClip();
}
I'm running Connect IQ SDK 3.1.5