Grid Glitch

[glenore]

Hello,
Wondering if anyone else is encountering this glitch when using the grid function. No matter the image file size or type (.tif, .jpg, or .png), whenever we have a grid to track which areas we have segmented already, we are unable to mark any of the quadrants in the top row or the leftmost column as anything but empty. This is not a hinderance to our work, but just something peculiar that might be an easy fix if it is something not liking my system.