The inside of the cable medallions are worked in a garter stitch. Ann Budd gives the following tip when working them, “If you remember that these center sts are knitted on the rounds that involve cable turns, it will be easy to remember when to knit and when to purl them.”
On Ravelry there seem to be several who have struggled with the pattern and think it was poorly written. If I could have looked over their shoulder I would have advised them to pay close attention to where the stitch markers are placed. I haven’t found this to be a difficult pattern but you do need to take care that the increases and decreases are done around one cable only. The second cable is worked without them. I believe you would have a disaster on your hands if you missed that one sentence in the pattern.
One of Cookies’ design tips is to place a stitch marker before the last stitch of the round as a reminder that a new round is about to begin. I’ve always placed mine at the beginning but think I might try her tip on another pair of socks some time. However, this pair might not be the one to try that on because the second cable marker is critical in this pattern. What about you? How do YOU mark round changes when you knit in the round?