This is a beautiful pattern indeed! Looking at the chart, I think it is just that the repeat is not blocked off fully for you. You don't need all of what is charted there. The basis of this design is two symmetrical rows mirroring each other in the middle and on the sides its the same just offset for the wide part of the design. That being said, your count for this should be 24 or 24+1 (the 1 for a stockinette column before the first repeat.)
In the picture, after row 24 the chart shows starting into another repeat and it doesn't even show a complete repeat. That is why you are coming up with an off count. I hope my explanation made it clearer. If not please ask more questions!