Full disclosure: I screwed up when I was making the sample for my Strippy HSTs for the PC quilters. Not only did I not follow my own pattern, I made the same mistake for half-a-quilt's-worth of blocks before I discovered the error. Which was unfixable at that point.
Here's what the block is supposed to look like. Note that the strips run perpendicular to the diagonal HST seam.
When making the blocks the HST seam should be oriented like this, going perpendicular to the strippy seams. See tutorial here for the block.
I ended up making another set of regular blocks so I had enough correct ones for the teaching sample, shown here: