Trouble with Weekend Rotation Schedule

Good Morning Everyone!

I've discovered a small problem with a rotation schedule I've been using. The sheet assigns a rotation of engineers to work a weekend day, without working two Saturdays or two Sundays in a row and rotating everyone about evenly. The problem I'm having is one instance when it reaches the end of *one* the rotations, it skips a Sunday entirely (G15 should be Sunday, July 14). I've looked at it, but can't figure out how to fix it. Can someone help me troubleshoot this?

Thanks you very much