It seems that Map rulings have been an issue for me over the years.
Like maps with beveled corners being released before rulings were well established.
Everybody was drawing los and shooting through beveled corners. Then years ago at a Regional event my opponent declared I couldn't draw los because it crossed this little red line that extended beyond the corner. I said, I thought you followed the grid line and not the line art. He called over the head judge who ruled I couldn't draw los. My opponent and the head judge were from the same area and said that's how they had always played it. I wasn't sure about the rule so I didn't question it. Afterwards, I looked up the ruling and found that I was right. Made a promise to myself to never let line art screw me over again.