My first set of errata... I suppose it was inevitable, after racing through so many patterns. Hopefully, the missing data is so obvious that you would have inserted it in your own mind as you were knitting.
Errata for Cabled Mug Cosy:
Row 85: k2tog tbl, k3, yo, k2tog, k2, k2tog
Row 89: k2tog tbl, k1, yo, k2tog, k2tog
The parts highlighted in red were absent from (but have now been added to) the published pattern. Apologies for any inconvenience.
If you see this post changing... nearly made an error in the errata! Think it's all fixed now... :)