[palosanto]

Mike I can confirm that I encounter this problem (missing strokes) quite often. I'm not using the radial menu and it happens only on the bottom of the screen when trying to annotate the last staff on a score. It reminds me of the problem we had months ago when the whole bottom of the page wasnt able to get annotated with the pen tool, remember? 
It's not as bad now but there's still a problem lingering around that area.