The pattern is correct, this is how I work all my i-cord edges: knit the first 3sts of every row, slip the last 3sts of every row purlwise with yarn in front. You can, of course, work the edges differently.

You are correct. The pattern is at fault. I have had to do the same as you.

Hi Kate! I-cord edging can be a bit confusing at first, but it is really simple. At the end of the round you bring the working yarn forward and slip the last 3 stitches (purlwise) onto your right needle. Now all your stitches are on the right needle, the working yarn is connected to the 4th stitch from the needle tip – this is how it should be. Turn your work to start the following round – the working yarn is at the back of your work, but it is not connected to the last stitch. Now knit as you normally would – insert the needle into the 1st stitch and using the working yarn make a knit stitch as you normally would. As a result the edge stitches will be pulled in and they will make a tube – the i-cord edging.

I’ve checked the pattern, and it is correct. The first and last 3 stitches form the i-cord edging, that is worked as follows: knit 3sts at the beginning of every row, slip the last 3 sts (with yarn in front) of every row.
I assume you’ve used another way to work the i-cord.