Pattern is flip-flopping

I am knitting an hourglass eyelet baby blanket. This is my second attempt. Both times, as soon as I got 6-8 inches into the pattern, I could see that midway up, the right side had become the wrong side. I have followed the pattern to the letter and have not done anything I can think of to have caused this maddening result (such as putting down the project midrow and picking it up in the wrong direction). I am probably going to abandon this project, but I’d at least like to learn something from it. Any ideas as to what could have caused my pattern to “flip”? Thanks!

You did the same row twice somewhere. Either 2 RS rows, or 2 WS rows. Mark the RS of the blanket with a safety pin or small piece of yarn in another color and when you begin a row, check to see if it’s supposed to be a RS or WS and do the correct row.

That makes perfect sense. And I see the importance of marking the sides. Thank you so much.