I'm going to take a stab at this, knowing full well I'm probably out of my depth.

I think you might be confusing melody with strum pattern. The notes on the photo that you posted are the melody. A strum pattern isn't meant to play the melody, but to provide underlying harmonic support for that melody. So the melody has only a loose relationship to the strum pattern in the sense that (in general) the particular note in the melody is within the chord being played in the strum pattern.

So if there is no note in the melody on a particular beat, that has no relationship to the strum pattern, which is, in a sense, the "band" backing up the "lead singer" of the song.

Strum pattern does not equal melody in the way that fingerpicking occasionally does.

I hope that sort of helps until someone wiser and more able to address your specific question comes along!