I think I figured it out… I’ll put it here in case it helps anyone else. you said the pattern is a multiple of 6, but it’s actually a multiple of 4 + 1 extra stitch, so 25 works because 24 is a multiple of 4 + 1 = 25. I was doing 30 and that’s an extra stitch because 28 is a multiple of 4 + 1 = 29, so 30 has an extra stitch.
The foundation chain is in the multiples of 4 plus 1. In this tutorial we have 25 chains, and also at the end of the 25 I added one more chain which is a turning chain and does not count as a stitch
